If you miss cozy, cheesy casseroles on a low-carb diet, this Keto Broccoli and Cauliflower Au Gratin with Sausage is a really good middle ground. It has that familiar creamy, baked comfort food feel, but keeps things lighter on the carbs by swapping the usual potatoes for broccoli and cauliflower and adding sausage for extra flavor and protein.

This is the kind of dish you can slide into the oven on a weeknight when you want something satisfying but don't feel like fussing with lots of separate pans and sides. Everything bakes together in one dish, the vegetables soak up the cheesy sauce, and the sausage brings just enough richness and seasoning so you don't need much else on the plate.

Think of it as a simple, no-drama dinner: a pan of tender broccoli florets and cauliflower florets covered in a creamy cheddar and Parmesan sauce, studded with browned Italian sausage, and baked until the top is golden and bubbling. Nothing fancy, just honest, straightforward food that happens to fit into a keto or low-carb way of eating.

Ingredients for this Keto Broccoli and Cauliflower Au Gratin with Sausage

Here's everything you'll need to pull this together. It looks like a lot written out, but once you start cooking, it flows pretty naturally.

2 cups broccoli florets, cut into bite-sized pieces
2 cups cauliflower florets, cut into bite-sized pieces
9 oz Italian sausage, casings removed
2 tbsp unsalted butter
3 cloves garlic, minced
3 oz cream cheese, softened
3/4 cup heavy cream
1 cup shredded sharp cheddar cheese, divided
1/2 cup grated Parmesan cheese, divided
1/2 tsp sea salt, or to taste
1/4 tsp black pepper
1/2 tsp dried Italian seasoning
1/4 tsp smoked paprika, plus a pinch more for topping (optional)
1 tbsp olive oil, for greasing the baking dish

If you can, go for fresh broccoli and cauliflower florets rather than frozen. They hold their texture better in the oven and don't release as much water into the sauce. The smoked paprika is optional, but it adds a subtle warmth and color that works nicely with the sausage.

Instructions

You'll cook the vegetables briefly, brown the sausage, make a quick cheese sauce right in the skillet, then bake everything together. It sounds like a lot of steps, but each one is pretty simple.

Preheat and prep the dish.
Preheat your oven to 375°F (190°C). Lightly grease a medium baking dish (around 8×8 inches or something similar) with the olive oil and set it aside. This keeps the cheesy edges from sticking too much.
Blanch the broccoli and cauliflower.
Bring a large pot of salted water to a boil. Add the broccoli florets and cauliflower florets and cook for about 3–4 minutes, just until they start to soften but are still firm in the center. You don't want them fully cooked here, because they'll finish in the oven.
Drain them well in a colander and let them sit for a few minutes so extra moisture can escape. This small pause helps keep the sauce from getting watery later.
Brown the sausage.
While the vegetables drain, place a large skillet over medium heat. Add the Italian sausage, breaking it up with a spatula as it cooks. Let it brown for about 6–8 minutes, until there are no pink bits left and you have nicely cooked crumbles.
If there's a lot of grease in the pan, carefully drain off the excess. You want some fat left for flavor, just not so much that the dish feels heavy.
Add butter and garlic.
Turn the heat down to low. Add the butter and minced garlic to the skillet with the sausage. Stir and cook for 30–60 seconds, just until the garlic smells fragrant. Keep an eye on it so it doesn't brown or burn; burnt garlic can overpower the whole dish.
Make the creamy base.
Add the cream cheese to the skillet. Stir gently as it softens and melts, coating the sausage. Pour in the heavy cream and keep stirring until the mixture looks smooth and starts to gently simmer around the edges.
Add the cheeses and seasoning.
Stir in 3/4 cup of the shredded sharp cheddar cheese and 1/4 cup of the grated Parmesan cheese. Keep stirring until they melt into the sauce.
Season the mixture with sea salt, black pepper, dried Italian seasoning, and 1/4 teaspoon smoked paprika. Give it a taste and adjust the salt if needed. This is your chance to get the seasoning just right before the vegetables go in.
Combine with the vegetables.
Add the drained broccoli florets and cauliflower florets to the skillet. Gently fold everything together so the vegetables are well coated in the sausage cheese sauce. Take your time here; you want every bite to have a bit of everything.
Transfer to the baking dish.
Spoon the mixture into your prepared baking dish and spread it into an even layer. A spatula works well to nudge everything into the corners.
Top with more cheese.
Sprinkle the remaining 1/4 cup grated Parmesan cheese and the remaining 1/4 cup shredded cheddar cheese evenly over the top. If you like a little extra color, dust a small pinch of smoked paprika across the surface.
Bake until bubbly and golden.
Slide the dish into the preheated oven and bake for 18–22 minutes, until the top is bubbling and just starting to turn golden around the edges.
If you want a deeper golden crust, switch the oven to broil for 1–2 minutes at the end. Just stay close and keep an eye on it; cheese can go from perfect to burnt pretty fast.
Rest and serve.
Take the Keto Broccoli and Cauliflower Au Gratin with Sausage out of the oven and let it rest for about 5–10 minutes. This short rest lets the sauce thicken up a bit and makes it easier to scoop out nice, neat portions.

Serve it as a complete meal in a bowl, or pair it with a simple green salad if you want something fresh on the side.

Cook and Prep Times

Prep time: 20 minutes
Cook time: 30 minutes
Total time: About 50 minutes
Servings: 4 portions

Nutritional information

The values below are an estimate for one serving when the dish is divided into four equal portions. It's meant as a general guide, not an exact lab analysis.

Calories: 520 kcal
Carbohydrates: 9g
Protein: 22g
Total fat: 44g
Saturated fat: 23g
Sodium: 860mg
Fiber: 3g
Sugar: 3g

Most of the carbs here come from the broccoli florets and cauliflower florets, which also bring fiber and a good amount of volume to the meal. The cream cheese, heavy cream, cheddar, Parmesan, and sausage provide the bulk of the fat and protein, which is what makes this Keto Broccoli and Cauliflower Au Gratin with Sausage feel so satisfying.

Frequently asked questions

Can I make this Keto Broccoli and Cauliflower Au Gratin with Sausage ahead of time?

Yes, you can. A simple way to do it is to prepare the recipe up to the point where the mixture is in the baking dish and topped with the remaining cheddar and Parmesan. Let it cool, cover it tightly, and refrigerate for up to a day before you plan to bake it.

When you're ready to cook, take the dish out of the fridge while the oven preheats. You may need to add a few extra minutes to the baking time since it will be going into the oven cold. Bake until the top is bubbling and hot in the center.

Can I use different sausage in this recipe?

You can, as long as you keep the basic idea the same. This version uses Italian sausage, but you can swap in a mild or hot style if you prefer more or less spice. Just make sure it's ground sausage that you can brown and crumble in the skillet.

Whatever sausage you choose, cook it thoroughly and drain off any excess grease before adding the butter, garlic, cream cheese, and heavy cream. That way the Keto Broccoli and Cauliflower Au Gratin with Sausage stays rich without feeling overly heavy.

How do I reheat leftovers without drying them out?

Leftovers reheat pretty well. For the oven, place the portion you want in a small oven-safe dish, cover it loosely with foil, and warm at around 325°F (165°C) until hot in the middle. If it looks a bit dry, you can drizzle a spoonful of heavy cream over the top before reheating to bring back some moisture.

For a quicker option, you can use the microwave. Put a serving of the Keto Broccoli and Cauliflower Au Gratin with Sausage on a microwave-safe plate, cover lightly, and heat in short bursts, stirring once or twice if needed. It won't be quite as crisp on top as the oven version, but it still tastes comforting and cheesy.

Either way, try not to overheat it. Warming it just until hot helps keep the broccoli florets and cauliflower florets from turning mushy and preserves the creamy texture of the sauce.