Cheesy Keto Broccoli Cauliflower Gratin

Prepare to tantalize your taste buds with the ultimate comfort food that perfectly aligns with your low-carb lifestyle: the Cheesy Keto Broccoli Cauliflower Casserole. This isn’t just a side dish; it’s a culinary masterpiece brimming with tender, vibrant florets of broccoli and cauliflower, enveloped in an incredibly rich, creamy, and undeniably cheesy sauce, all crowned with crispy, savory crumbled bacon. Each spoonful delivers a symphony of flavors and textures that will satisfy even the most discerning palates, making it an instant favorite at any meal. So easy to prepare, this casserole promises to be a keto dream come true, ensuring everyone reaches for a second helping!

Overhead photo of a large white rectangular casserole dish holding a baked keto broccoli cauliflower casserole topped with lots of cheese and pieces of bacon.

Why This Cheesy Keto Broccoli Cauliflower Casserole is a Must-Try

This isn’t just another low-carb recipe; it’s a game-changer that combines incredible flavor with remarkable ease and versatility. Here’s what makes our Keto Broccoli Cauliflower Casserole truly exceptional:

Irresistible Flavor Profile and Texture

Imagine a harmonious blend of three types of perfectly melted cheese – typically a mix of sharp cheddar and creamy mozzarella for that ideal gooey, stretchy texture and deep flavor. This cheesy foundation is complemented by the rich tang of sour cream and the luxurious smoothness of cream cheese and heavy cream, creating a velvety sauce that coats every tender floret.
Adding to this creamy delight are savory, crispy bacon crumbles, providing a delightful textural contrast and a smoky, salty kick that elevates the entire dish. The combination of tender broccoli and cauliflower, coupled with the varied textures of the cheese and bacon, ensures an exciting experience with every bite. It’s a truly indulgent experience without breaking your keto macros.

Unmatched Convenience and Versatility

Whether you’re looking to utilize fresh, seasonal broccoli and cauliflower from your local market or need a quick solution using those trusty bags of frozen veggies from your freezer, this recipe adapts beautifully. Frozen steamer bags, in particular, simplify the preparation process, making this a perfect option for busy weeknights when time is of the essence. You’ll be amazed at how easily you can bring such a sophisticated-tasting dish to your table.
This casserole is designed for both seasoned home cooks and culinary beginners. The straightforward steps and forgiving nature of the ingredients mean you can achieve fantastic results with minimal effort. It’s a wonderful recipe to have in your repertoire for meal prep, family dinners, or potlucks.

Endless Customization for Every Palate

This Keto Broccoli Cauliflower Casserole is a fantastic canvas for your culinary creativity. Feel free to experiment with different cheeses; a spicy pepper jack can add a wonderful kick, or a smoked gouda can introduce a unique depth of flavor. Don’t limit yourself to cheddar and mozzarella – explore!
Beyond cheese, consider seasoning your veggies with an array of spices. A dash of garlic powder, onion powder, smoked paprika, or a pinch of red pepper flakes can transform the flavor profile. You can even switch up the bacon type; try a maple-flavored bacon for a hint of sweetness, or a spicy jalapeño bacon for extra heat. Consider adding other low-carb vegetables like sautéed spinach, diced bell peppers, or even some cooked, shredded chicken for a more substantial meal. Make it truly your own with unique additions!

Expert Tips for Casserole Perfection

Achieving a truly exceptional casserole comes down to a few key details. Follow these chef-approved tips to ensure your Keto Broccoli Cauliflower Casserole is nothing short of spectacular:

Mastering Your Vegetables: Fresh or Frozen

For the best texture and flavor, steaming your broccoli and cauliflower florets to a tender-crisp stage is crucial. You want them cooked enough to be soft, but not mushy, as they will continue to cook in the oven. If you’re new to steaming, we have a comprehensive guide that makes it incredibly simple: How to Steam Cauliflower (and Broccoli) Perfectly. This method ensures your vegetables retain their nutrients and vibrant color.
Alternatively, for ultimate convenience, especially on a busy weeknight, opt for microwaveable steamer bags of frozen broccoli and cauliflower. Simply follow the package instructions to steam them, then drain any excess water thoroughly before incorporating them into the casserole. This quick shortcut allows you to cut down on prep time without sacrificing quality.

The Secret to Superior Cheese Melt

This tip cannot be stressed enough for any cheesy casserole: **always shred your own cheese directly from the block.** While pre-shredded cheeses offer convenience, they typically contain anti-caking agents like cellulose or potato starch. These fillers add unnecessary carbohydrates (which can impact your keto macros) and, more importantly, prevent the cheese from melting into that smooth, gooey consistency we all crave.
Freshly shredded cheese melts beautifully and integrates seamlessly into the sauce, creating a richer, more luxurious texture and flavor. It takes only a few extra minutes to shred a block of cheese, and the superior results are absolutely worth the minimal effort. This simple step will elevate your casserole from good to extraordinary.

Ingredient Temperature Matters for Creaminess

For the smoothest, most homogenous cheese sauce, ensure your full-fat cream cheese is softened to room temperature, but not warm or melted. This allows it to blend effortlessly with the sour cream and heavy whipping cream, preventing lumps and creating a perfectly silky base.
Similarly, bringing your heavy whipping cream to room temperature will help it emulsify more easily with the other dairy ingredients, contributing to the overall creamy texture of the casserole. A little foresight in letting these ingredients warm up slightly will make a big difference in the final consistency of your sauce.

A scoop of keto broccoli cauliflower casserole being lifted out of a casserole dish with a large spoon.

More Low-Carb Delights You’ll Love

If you’re a fan of delicious, keto-friendly recipes, be sure to explore some of our other popular creations. From sweet treats to savory mains, we’ve got something for everyone:

Keto Whipped Cream
Chick-fil-A Style Keto Chicken Nuggets (with Keto Chick-fil-A Sauce)
Keto Smothered Pork Chops
Perfect Keto Lemon Curd (4 Ingredients)
Keto Gumbo
Whipped Cottage Cheese (Sweet or Savory)
2-Ingredient Keto Magic Shell
Cheesy Keto Green Beans
Keto Tamales
Cheesy Italian Sausage & Bell Pepper Casserole
Tangy Keto Lemon Bars
Keto Tacos with Homemade Keto Tortillas

Keto Broccoli Cauliflower Casserole

Prep: 30 minutes

Cook: 20 minutes

Total: 50 minutes

Indulge in this creamy and cheesy broccoli cauliflower casserole, a true keto dream, generously packed with tender florets and crispy bacon crumbles. It’s the perfect low-carb side dish or a light main course that’s sure to impress.

Cheryl Malik

Print Recipe

12
servings

Ingredients

For the Cheesy Keto Casserole Base

▢ 1 small head fresh broccoli, chopped into florets (approximately 2-3 cups)
▢ 1 small head fresh cauliflower, chopped into florets (approximately 2-3 cups)
▢ ½ cup full-fat sour cream
▢ 4 ounces full-fat cream cheese, softened to room temperature
▢ ¼ cup heavy whipping cream, at room temperature
▢ ½ cup freshly shredded mozzarella cheese (see Notes for best results)
▢ ½ cup freshly shredded cheddar cheese (see Notes for best results)
▢ 2 ounces sweet onion, diced (about half of 1 small onion; optional, but adds a lovely savory note)
▢ 8 slices bacon, cooked until crispy and crumbled
▢ Salt, to taste
▢ Freshly cracked black pepper, to taste

For the Golden Topping

▢ ½ cup freshly shredded mozzarella cheese (for topping)
▢ ½ cup freshly shredded cheddar cheese (for topping)

Equipment

Oven
Large saucepan (optional, for steaming fresh veggies)
Steamer basket (optional, for steaming fresh veggies)
Medium bowl
9×13 inch casserole dish
Neutral-flavored cooking spray
Large mixing bowl
Silicone spatula or sturdy spoon

Step-by-Step Instructions

Preparing Your Vegetables to Perfection

If using fresh broccoli and cauliflower: Fill a large saucepan with 2 to 3 inches of water. Place a steamer basket into the saucepan, ensuring the water does not touch the bottom of the basket (leave approximately 4 to 5 inches between the water and the basket).
Place the saucepan on your stovetop over high heat and bring the water to a rapid boil. Once boiling, carefully add the broccoli florets (from the 1 small head fresh broccoli) to the steamer basket. Immediately reduce the heat to medium.
Steam the broccoli, uncovered, for 5 to 7 minutes, or until the florets are tender-crisp and can be easily pierced with a fork. Promptly transfer the steamed broccoli to a medium bowl and set it aside to cool slightly.
Refill the saucepan with water as needed, ensuring it still does not touch the bottom of the steamer basket. Return the saucepan to the stovetop and increase the heat to high until the water is boiling rapidly again.
Once boiling, add the cauliflower florets (from the 1 small head fresh cauliflower) to the steamer basket and immediately reduce the heat to medium.
Steam the cauliflower, uncovered, for approximately 10 minutes or until the florets are tender-crisp and easily pierced with a fork. Transfer the steamed cauliflower to the same medium bowl as the broccoli and set aside to cool completely. Allowing them to cool slightly helps prevent a watery casserole.

Crafting the Creamy Casserole Mixture

Preheat your oven to 375° Fahrenheit (190°C). Lightly spray a 9×13 inch casserole dish with a neutral-flavored cooking spray to prevent sticking, and set it aside.
In a large mixing bowl, combine the ½ cup full-fat sour cream, 4 ounces softened full-fat cream cheese, ¼ cup room temperature heavy whipping cream, ½ cup freshly shredded mozzarella (for the base), and ½ cup freshly shredded cheddar (for the base). Stir these ingredients vigorously with a silicone spatula or sturdy spoon until they are thoroughly incorporated and form a smooth, creamy sauce.
Once the creamy base is well combined, add the cooled steamed broccoli, cooled steamed cauliflower, 2 ounces diced sweet onion (if using), 8 slices cooked and crumbled bacon, and season generously with salt and freshly cracked black pepper to taste. Gently stir all ingredients together until everything is fully incorporated, ensuring the vegetables and bacon are thoroughly coated in the rich sour cream and cheese mixture. Be careful not to mash the vegetables.
Transfer the entire mixture into the prepared casserole dish. Using your spatula, spread the mixture out evenly across the bottom of the dish, making sure to reach all edges and corners for uniform cooking.
Evenly sprinkle the remaining ½ cup freshly shredded mozzarella and ½ cup freshly shredded cheddar across the top of the broccoli cauliflower layer. This will form a beautiful, golden crust. Cover the casserole dish securely with aluminum foil.

Baking to Golden Perfection and Serving

Place the covered casserole dish into your preheated oven. Bake for 20 minutes, or until the cheese underneath is thoroughly melted and the mixture is bubbling around the edges.
Carefully remove the casserole dish from the oven. If you desire a golden-brown, crispy cheese topping, remove the foil and return it to the oven for an additional 5-10 minutes, or until the top is beautifully browned and bubbly. Keep a close eye on it to prevent burning.
Let the casserole stand for 5 minutes after removing it from the oven before serving. This allows the cheeses and liquids to set, making for cleaner scoops and an even creamier texture. Serve warm and enjoy!

Important Recipe Notes & Variations

Steaming Vegetables: While fresh vegetables offer the best texture and flavor, using frozen broccoli and cauliflower florets in microwaveable steamer bags is a fantastic time-saving option. Ensure they are fully cooked but not mushy, and drain any excess water to prevent your casserole from becoming watery.
Cheeses: For the ultimate creamy melt and to avoid unnecessary carbs from anti-caking agents, we strongly recommend shredding your own cheese directly from the block rather than using pre-packaged shredded varieties. This makes a noticeable difference in both taste and texture.
Storage: Leftover casserole can be stored in an airtight container in the refrigerator for up to 3-4 days.
Make Ahead: You can prepare the vegetable and cheese mixture (steps 1-9) a day in advance. Store it covered in the casserole dish in the refrigerator. Before baking, let it come to room temperature for about 30 minutes, then proceed with sprinkling the topping cheese and baking as instructed, possibly adding 5-10 minutes to the covered baking time.
Reheating: Reheat individual portions in the microwave until warm throughout, or cover the entire casserole with foil and reheat in a 300°F (150°C) oven until bubbly and hot.
Variations:
- Spicy Kick: Add a pinch of red pepper flakes or a dash of hot sauce to the cheese mixture.
- Herbaceous Freshness: Stir in a tablespoon of fresh chopped chives, parsley, or dill.
- Protein Boost: Mix in cooked shredded chicken, diced ham, or cooked ground sausage for a heartier meal.
- Garlic Lover’s Dream: Sauté 2-3 cloves of minced garlic with the onion (if using) before adding to the mixture for an extra layer of flavor.

Nutritional Information (Per Serving)

These nutritional values demonstrate how well this casserole fits into a ketogenic diet, with low total and net carbs, moderate protein, and healthy fats.

The number of total servings shown is approximate. Actual number of servings will depend on your preferred portion sizes.

Nutritional values shown are general guidelines and reflect information for 1 serving using the ingredients listed, not including any optional ingredients. Actual macros may vary slightly depending on specific brands and types of ingredients used.

To determine the exact weight of one serving, prepare the recipe as instructed. Weigh the finished recipe (excluding the container) and divide by your desired number of servings. The result will be the weight of one serving.

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