Chicken Spinach Mushroom Low Carb

The first time I made this chicken and spinach casserole, I was trying to use up leftover rotisserie chicken and a container of mushrooms that were threatening to turn. My husband took one bite and asked if I could make it again next week, except maybe double the recipe. That kind of request doesn't happen often in our kitchen.

Last winter, when we were buried under deadlines and freezing temperatures, this dish became our Friday night comfort food tradition. My sister dropped by unexpectedly one Friday while it was in the oven. She ended up staying for dinner and taking the recipe home with her, which is pretty much the highest compliment she can pay anything.

Ingredients

• 2 cups cooked chicken breast: I usually grab a rotisserie chicken from the grocery store when I'm short on time, but leftover baked or poached chicken works beautifully too
• 4 cups fresh spinach: Don't be intimidated by how much this is, it wilts down dramatically and adds such a nice earthy flavor that balances the rich cream
• 2 cups mushrooms: Cremini mushrooms have more flavor than white button mushrooms, but either will work in a pinch
• 1 small onion: Finely chopped so it cooks down soft and sweet instead of staying crunchy
• 3 cloves garlic: Fresh minced garlic really makes a difference here, don't be tempted to use the jarred stuff
• 1 cup mozzarella cheese: Shredded from a block melts so much better than the pre-shredded bags that have anti-caking coating
• 1/4 cup parmesan cheese: Freshly grated adds that salty, nutty finish that makes the whole dish taste restaurant quality
• 1/2 cup heavy cream: This is what creates that luxurious sauce without any flour or starch
• 2 tablespoons olive oil: For sautéing the vegetables and building that flavorful base
• 1 teaspoon Italian seasoning: A simple blend that ties all the Italian flavors together perfectly
• Salt and pepper: Season generously at each step, not just at the end, for layers of flavor

Instructions

Preheat your oven to 375°F:

Lightly grease a 9x13 inch baking dish with butter or cooking spray while the oven heats up.

Sauté the aromatics:

Heat the olive oil in a large skillet over medium heat, then add the onions and mushrooms, cooking for 5 to 7 minutes until they're soft and starting to turn golden brown.

Add the garlic:

Stir in the minced garlic and cook for just 1 minute until it becomes fragrant, being careful not to burn it.

Wilt the spinach:

Add the spinach to the skillet and stir until it's completely wilted, then season everything with salt, pepper, and Italian seasoning.

Layer the chicken:

Spread your cooked chicken pieces evenly across the bottom of your prepared baking dish.

Add the vegetables:

Spread the sautéed mushroom, spinach, and onion mixture over the chicken in an even layer.

Drizzle with cream:

Pour the heavy cream evenly over the entire dish so it can seep down through all the layers.

Add the cheese:

Sprinkle the mozzarella and parmesan cheese over everything, covering the surface completely.

Bake until golden:

Bake uncovered for 20 to 25 minutes until the cheese is melted, bubbly, and starting to turn golden brown on top.

Let it rest:

Remove from the oven and let the casserole rest for 5 minutes before serving, this helps it set up slightly and makes serving much easier.

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This recipe has saved me on countless busy weeknights when I want something that feels special but only takes about 15 minutes of active prep time. My mom now makes it for her book club meetings, and apparently everyone asks for the recipe every single time.

Make It Your Own

Sometimes I'll add a pinch of red pepper flakes when I'm seasoning the vegetables for a little warmth that cuts through the rich cream and cheese. It's not enough to make it spicy, just enough to add depth and keep things interesting.

Storage Solutions

This casserole keeps beautifully in the refrigerator for up to 4 days, and I actually think the flavors improve after a night in the fridge. The cream has time to really seep into every nook and cranny.

Serving Suggestions

While this is absolutely complete as a standalone low carb meal, I sometimes serve it with a simple green salad dressed with lemon vinaigrette to cut through the richness. Caulliflower rice also works beautifully if you're missing that texture.

• Let the casserole rest before serving so it holds its shape better on the plate
• A sprinkle of fresh parsley or basil right before serving adds a nice pop of color
• Leftovers reheat perfectly in the microwave at 50 percent power to prevent the cheese from separating

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This is one of those recipes that makes you feel like you really know what you're doing in the kitchen, even though it comes together with almost zero effort. That's my favorite kind of cooking.

Recipe Q&A

→ Can I use raw chicken instead of cooked?

While possible, raw chicken would need to be cooked through completely before baking. Using pre-cooked chicken ensures the dish finishes in the stated 25-minute baking time and prevents the vegetables from becoming overcooked while waiting for the chicken to reach safe internal temperature.

→ What cheese substitutions work well?

Sharp cheddar, gruyère, or Swiss can replace or complement the mozzarella. For the parmesan, try pecorino romano or asiago for similar salty, nutty notes. Just keep the total cheese quantity consistent for proper texture.

→ Can I make this dairy-free?

Substitute the heavy cream with full-fat coconut milk or unsweetened almond milk mixed with a teaspoon of tapioca starch for thickness. Use dairy-free cheese alternatives, though melting results may vary slightly from traditional dairy cheeses.

→ Why do my mushrooms release so much water?

Mushrooms naturally contain high water content. The key is to sauté them thoroughly over medium heat for the full 5–7 minutes, allowing the moisture to evaporate before adding other ingredients. This concentrates their flavor and prevents a watery final dish.

→ Can I freeze this casserole?

Yes, assemble the entire dish before baking, wrap tightly in plastic and foil, and freeze for up to 3 months. Thaw overnight in the refrigerator before baking as directed. Alternatively, bake first, then freeze individual portions for quick reheating.

→ What vegetables can I add or substitute?

Bell peppers, zucchini, or broccoli florets work beautifully alongside or instead of the spinach. For keto variations, try cauliflower rice or chopped kale. Just adjust quantities to maintain the same casserole consistency.