This Chicken Spinach Cauliflower Casserole is made with shredded chicken, wilted spinach, and roasted cauliflower, all baked together in a creamy cheddar sauce. It’s a low-carb dinner that still eats like a full comfort food meal, with the cauliflower standing in for a heavier starch.

I make this on weeknights when I want something filling that covers protein and vegetables in one dish. It also reheats well, so it’s good for lunches through the week. I like serving this next to high-protein low carb casseroles or a One Pot Beef and Chickpea Stew for a couple of hearty dinner options.

If you like hearty, low-carb casseroles like this one, these are worth trying too:

Ingredients You’ll Need

Roasting the cauliflower first, rather than boiling it, keeps it from turning watery once baked into the sauce. Sharp cheddar cheese gives this the most flavor, so don’t skip it even though it’s easy to reach for something milder.

Ingredients

1 large head cauliflower, cut into florets
2 tbsp olive oil
1 tbsp butter
4 cups fresh spinach
3 tbsp all-purpose flour
2 cups milk
2 cups cooked chicken, shredded
2 cups shredded cheddar cheese, divided
1/2 tsp garlic powder
1/2 tsp dried thyme
Salt and pepper, to taste

Directions

Preheat your oven to 400°F and line a baking sheet with parchment paper.
Toss the cauliflower florets with the olive oil and spread them out in a single layer.
Roast for 20 minutes, until fork-tender and lightly browned at the edges.
While the cauliflower roasts, melt the butter in a skillet over medium heat.
Add the spinach and cook until wilted, about 2 to 3 minutes.
Remove from the heat and set aside.
In the same skillet, whisk in the flour and cook for about a minute, stirring constantly.
Slowly whisk in the milk, continuing to whisk until the sauce thickens, about 4 to 5 minutes.
Stir in the garlic powder, thyme, salt, and pepper.
Remove the sauce from the heat and stir in 1 cup of the shredded cheddar until melted and smooth.
Reduce the oven temperature to 375°F.
In a large bowl, combine the roasted cauliflower, wilted spinach, shredded chicken, and the cheese sauce, stirring gently to coat everything.
Transfer the mixture to a greased 9×13-inch baking dish.
Sprinkle the remaining cheddar cheese evenly over the top.
This one takes a bit of prep across a few steps, just so you know, but the actual baking is hands-off.
Bake for 20 to 25 minutes, until golden and bubbly.
Let it rest for 5 minutes before serving.
Serve hot and enjoy!

Important Recipe Notes

Roast the cauliflower instead of boiling it. Boiled cauliflower holds extra water that can water down the cheese sauce once everything bakes together.
Add cheddar cheese, don’t skip it. It’s the main source of flavor in this dish, both stirred into the sauce and sprinkled on top for that golden, bubbly finish.
Wilt the spinach before mixing it in. This shrinks its volume and keeps it from releasing too much water once the whole dish bakes together.
Rotisserie chicken is the fastest option here, but any leftover cooked chicken breast or thigh meat works just as well.
Store leftovers in an airtight container in the fridge for up to 4 days. Reheat in the oven at 350°F for the best texture, or in the microwave if you’re short on time.
This freezes reasonably well, though the sauce can separate slightly after thawing. Stir well when reheating to bring it back together.

How to Serve, Store & Customize This Recipe

Serving: Serve hot straight from the baking dish with a simple green salad on the side. This is filling enough on its own to make a complete low-carb dinner.

Storing: Keep leftovers in an airtight container in the fridge for up to 4 days. Reheat in the oven at 350°F, covered with foil, until warmed through.

Customizing: Add crumbled cooked bacon on top for extra richness, or swap the cheddar for a mix of gruyere and parmesan. A pinch of red pepper flakes in the sauce adds some heat if you want it spicier.