There’s something undeniably comforting about a bubbling casserole fresh from the oven. Imagine the intoxicating aroma of cheese melting to golden perfection, mingling with the earthy notes of broccoli and cauliflower, all heightened by the savory hint of smoked sausage. This Keto Broccoli and Cauliflower Au Gratin with Sausage is not just a dish; it’s a cozy embrace at the end of a busy day, designed to satisfy your cravings without compromising your dietary goals.

When the week starts to wear you down, I find solace in whipping up this creamy, cheesy delight. Whether you’re following a strict keto lifestyle or simply seeking a hearty alternative to the fast food humdrum, this recipe offers both ease and flavor in each bite. With the versatility to swap in your favorite ingredients, it’s a dish that guarantees comfort while remaining guilt-free. Let’s dive into how to bring this wholesome, delicious meal to your table tonight!

Why Choose Keto Broccoli & Cauliflower Au Gratin with Sausage?

Indulgent comfort: This dish delivers rich, creamy flavors that satisfy your comfort food cravings while staying in line with your keto goals.
Quick prep: With straightforward instructions, you can whip up this casserole in under an hour, making it perfect for busy weeknights.
Versatile ingredients: Feel free to use your favorite sausages or swap veggies for whatever you have on hand—zucchini or spinach works beautifully!
Crowd-pleaser: Even those not on a keto diet will love this dish; its cheesy, hearty goodness appeals to all palates.
Meal prep-friendly: Leftovers store well in the fridge or freezer, making it a great option for meal planning.
For more delicious ideas that fit your lifestyle, check out my meal planning tips.

Keto Broccoli & Cauliflower Au Gratin Ingredients

For the Casserole
• Broccoli Florets – Provides texture and nutritional benefits; can substitute with spinach for a different flavor profile.
• Cauliflower Florets – Acts as a low-carb base, mimicking traditional potato au gratin.
• Smoked Sausage (12 oz, sliced) – Adds hearty protein and a smoky flavor to the dish; turkey or chicken sausage can be used for a leaner option.
• Butter (2 tbsp) – Used for sautéing and adds richness.
• Garlic (2 cloves, minced) – Enhances flavor; garlic powder is a suitable substitute.
• Heavy Cream (1 cup) – Creates the creamy cheese sauce; consider coconut milk for a dairy-free option.
• Dijon Mustard (1 tsp) – Adds a tangy depth to the sauce.
• Smoked Paprika (1/2 tsp) – Brings a smoky flavor; use regular paprika if smoked is unavailable.
• Onion Powder (1/2 tsp) – Enhances overall flavor.
• Red Pepper Flakes (1/4 tsp, optional) – Adds a hint of heat.
• Shredded Cheddar Cheese (2 cups, divided) – Main source of cheesiness; offers a rich texture, or mix with Monterey Jack for variation.
• Grated Parmesan Cheese (1/2 cup) – Adds a salty, nutty flavor to the dish.
• Green Onions (2, sliced for garnish) – Adds freshness and color.
• Salt and Black Pepper – To taste.

How to Make Keto Broccoli & Cauliflower Au Gratin with Sausage

Preheat your oven to 375°F (190°C) and grease a medium casserole dish to ensure that nothing sticks during baking. This prepares the stage for your delicious layers!
Steam or lightly boil the broccoli and cauliflower florets for about 3–4 minutes until they are just tender. Drain well to prevent excess moisture, which keeps your gratin creamy but not watery.
Melt the butter in a skillet over medium heat, then add the minced garlic. Sauté until fragrant, about 1-2 minutes, to infuse your dish with aromatic flavor.
Combine heavy cream, Dijon mustard, smoked paprika, onion powder, and optional red pepper flakes into the skillet. Let this delightful mixture simmer until slightly thickened, which takes about 3-4 minutes.
Mix in 1 1/2 cups of cheddar cheese and the grated Parmesan cheese. Stir until smooth and creamy, seasoning with salt and pepper to your taste, for that perfectly balanced flavor.
Layer the broccoli, cauliflower, and sliced sausage in the greased casserole dish. Pour the luscious cheese sauce evenly over the top, ensuring every bite will be cheesy goodness.
Sprinkle the remaining cheddar cheese on top to create that irresistible golden crust while baking, making it visually appealing and mouthwatering.
Bake uncovered for 20–25 minutes until bubbly and golden brown. Allow the gratin to set for a few minutes before serving, ensuring it holds its shape well on your plate.

Optional: Garnish with sliced green onions for a pop of freshness and color!

Exact quantities are listed in the recipe card below.

Storage Tips for Keto Broccoli & Cauliflower Au Gratin with Sausage

Fridge: Store leftovers in an airtight container for up to 4 days, ensuring it retains its rich flavors while staying fresh.
Freezer: This dish can be frozen for up to 2 months—just make sure to cool completely before wrapping securely to prevent freezer burn.
Thawing: Thaw overnight in the fridge for best results. Reheat in the oven at 350°F (175°C) until heated through for a delicious, bubbly meal again.
Reheating: For a crispy topping, cover with foil during reheating and remove for the last 5 minutes to achieve that golden-brown finish on your Keto Broccoli & Cauliflower Au Gratin with Sausage.

What to Serve with Keto Broccoli & Cauliflower Au Gratin with Sausage?

This creamy, cheesy casserole is truly satisfying on its own, but pairing it with complementary sides will elevate your meal to new heights.

Fresh Green Salad: A crisp salad with mixed greens and a light vinaigrette adds a refreshing contrast to the rich gratin, making each bite feel vibrant.
Roasted Asparagus: The tender crunch of roasted asparagus drizzled with lemon brings a zesty brightness that balances the creamy dish beautifully.
Garlic Breadsticks: Soft breadsticks infused with garlic make for a delightful dipping experience, perfect for soaking up the luscious cheese sauce.
Sautéed Spinach: Lightly sautéed spinach with garlic complements the flavors without overpowering them, providing a gentle earthiness and additional nutrition.
Herbed Quinoa: A fluffy quinoa side with fresh herbs offers a nutty flavor and subtle texture that pairs well with the cheesy goodness.
Low-Carb Wine: A chilled glass of dry white wine becomes a lovely accompaniment, enhancing the overall dining experience without breaking your keto rules.
Berry Coconut Sorbet: Finish off your meal with a light and fruity sorbet that cleanses the palate—refreshing and guilt-free after a hearty casserole!

Expert Tips for Keto Broccoli & Cauliflower Au Gratin

Vegetable Caution: Avoid overcooking broccoli and cauliflower before baking; they should be just tender to maintain structure and bite.
Smooth Sauce: Ensure the cheese sauce is completely smooth before pouring it over the vegetables for a creamy texture throughout the dish.
Let It Rest: Allow the casserole to sit for a few minutes after baking; this helps it set properly, making serving easier and neater.
Flavor Flexibility: Experiment with different cheese combinations, like Gruyère or mozzarella, to customize the flavor of your Keto Broccoli & Cauliflower Au Gratin.
Proper Storage: Store leftovers in an airtight container in the fridge for up to 4 days, or freeze for up to 2 months—thaw overnight before reheating for best results.

Make Ahead Options

These Keto Broccoli and Cauliflower Au Gratin with Sausage are perfect for meal prep lovers! You can steam the broccoli and cauliflower florets up to 24 hours in advance, then store them in an airtight container in the refrigerator. Prepare the cheese sauce and sauté the sausage, refrigerating them separately as well—just remember to cool everything completely before storing to prevent sogginess. When you’re ready to bake, simply layer the prepped vegetables and sausage in your greased casserole dish, pour the cheese sauce over the top, sprinkle with additional cheese, and then bake as directed. You’ll have a warm, comforting meal ready to enjoy with minimal effort!

Keto Broccoli & Cauliflower Au Gratin Variations

Feel free to make this dish your own with these delightful twists, ensuring every bite is just right for you!

Dairy-Free: Substitute heavy cream with coconut milk for a luscious, dairy-free version that maintains creaminess without the lactose.
Flavor Boost: Stir in some fresh herbs like thyme or basil into the cheese sauce to elevate the dish with aromatic freshness.
Cheese Change: Swap out sharp cheddar for creamy Gruyère or mozzarella for a completely new cheesy experience that melts beautifully.
Spicy Kick: Add more red pepper flakes or a dash of cayenne pepper for an extra zing that tantalizes the taste buds!
Veggie Swap: Replace the broccoli and cauliflower with sautéed zucchini or mushrooms for a delicious variation that still stays low-carb.
Meat Variation: Use chorizo or Italian sausage to infuse the dish with a bold flavor profile that pairs harmoniously with the cheesy goodness.
Crunchy Topping: For a crispy finish, sprinkle panko breadcrumbs mixed with Parmesan cheese on top before baking.
Low-Sodium Option: Reduce salt and use low-sodium broth in place of some heavy cream for a heart-healthier alternative without sacrificing flavor.

Let your creativity shine through as you enjoy this comforting dish tailored to fit your taste!

Keto Broccoli & Cauliflower Au Gratin with Sausage Recipe FAQs

What type of broccoli and cauliflower should I use?
Absolutely! Fresh broccoli and cauliflower florets will give the best texture and flavor to your dish. Look for firm florets with vibrant colors. If you notice dark spots or wilting, it’s best to avoid those. You can also use frozen veggies in a pinch, just remember to thaw and drain them well before adding to your casserole.

How should I store leftovers from the Keto Broccoli & Cauliflower Au Gratin?
The more the merrier! Store any leftovers in an airtight container in the fridge for up to 4 days. For long-term storage, place them in a freezer-safe container or a heavy-duty freezer bag and freeze for up to 2 months. Make sure to cool the dish completely before freezing to preserve its flavor and texture.

Can I freeze Keto Broccoli & Cauliflower Au Gratin with Sausage?
Certainly! This dish freezes exceptionally well. To freeze, let it cool completely, then wrap it tightly in plastic wrap followed by aluminum foil. This will help prevent freezer burn. When you’re ready to enjoy it again, thaw it overnight in the refrigerator and reheat in the oven at 350°F (175°C) until bubbly.

What if my cheese sauce doesn’t melt smoothly?
No worries! If your cheese sauce isn’t melting smoothly, it may be due to the temperature or the type of cheese used. Make sure to use freshly shredded cheese, as pre-shredded options contain anti-caking agents that can prevent a smooth melt. If the sauce feels too thick, you can stir in a splash of heavy cream or milk to loosen it up while heating it gently over low heat.

Can I make this dish dairy-free?
Absolutely! To make your Keto Broccoli & Cauliflower Au Gratin dairy-free, you can substitute heavy cream with canned coconut milk for a creamy base. Ensure you’re using dairy-free cheese alternatives to keep the richness while adhering to your dietary preferences. Additionally, turmeric can be added for a hint of color without the dairy.