Chicken Spinach & Mushroom Low Carb Oven Dish

The first time I made this chicken and spinach casserole, I was trying to use up a rotisserie chicken from the night before. My kitchen smelled like garlic and mushrooms within minutes, and I knew I was onto something better than my usual leftover chicken routine. The way the cream bubbles up through the cheese as it bakes is pure kitchen magic. Now it is my go-to when I want something comforting but still light enough for a weeknight.

Last winter my sister came over for dinner, still recovering from the flu. I popped this casserole in the oven while we caught up on the couch. When I pulled it out, bubbling and golden, she actually sat up straighter at the smell. She ate two helpings and said it was the first thing that actually tasted good in days. Sometimes simple food hits different.

Ingredients

• 2 cups cooked chicken breast: Rotisserie chicken is my shortcut, but any leftover cooked chicken works beautifully here
• 4 cups fresh spinach: It looks like a mountain when raw but wilts down into the perfect amount
• 2 cups mushrooms, sliced: Button or cremini both work, just slice them evenly so they cook at the same rate
• 1 small onion, finely chopped: The sweetness balances the earthy mushrooms perfectly
• 3 cloves garlic, minced: Do not skip this, it makes the whole kitchen smell incredible
• 1 cup mozzarella cheese, shredded: Freshly shredded melts better than the pre-shredded stuff
• 1/4 cup parmesan cheese, grated: Adds this salty, nutty depth that makes the dish feel finished
• 1/2 cup heavy cream: This is what makes the sauce so luxurious without any flour
• 2 tablespoons olive oil: For sautéing the vegetables until they are golden and fragrant
• 1 teaspoon Italian seasoning: Dried oregano, basil, and thyme blend works perfectly here
• Salt and pepper, to taste: Season generously as you cook each layer

Instructions

Preheat your oven:

Heat it to 375°F and grease a 9×13 inch dish with a little butter or oil

Sauté the vegetables:

Heat olive oil in a large skillet over medium heat, then cook onions and mushrooms for 5–7 minutes until soft and lightly browned

Add the garlic:

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

Wilt the spinach:

Toss in the spinach and cook until it collapses, then season everything with salt, pepper, and Italian seasoning

Start layering:

Spread the chopped chicken evenly across the bottom of your prepared casserole dish

Add the vegetable layer:

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

Drizzle the cream:

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

Add the cheeses:

Sprinkle mozzarella and parmesan over the top until everything is covered in a cheesy blanket

Bake until golden:

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

Let it rest:

Wait 5 minutes before serving so the sauce has time to set up slightly

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This recipe has become my Sunday meal prep staple. I make it on Sunday afternoon and then I have lunch sorted for half the week. Something about the way the flavors meld after a day in the fridge just works.

Making It Your Own

Sometimes I swap in kale for spinach when that is what I have in the fridge, and it holds up beautifully. The texture is slightly heartier but still works perfectly with the cream sauce.

Serving Suggestions

I like serving this with a simple arugula salad dressed with lemon and olive oil. The brightness cuts through all that rich, creamy goodness perfectly.

Storage & Reheating

This keeps in the refrigerator for up to 4 days in an airtight container. Reheat individual portions in the microwave at 50% power so the cream does not separate.

• Freeze portions in freezer-safe containers for up to 3 months
• Thaw overnight in the refrigerator before reheating
• Add a splash of cream when reheating if it looks dry

Save

Hope this becomes one of your weeknight staples too. There is something so satisfying about a dish that comes together this easily but tastes like you spent hours on it.

Recipe Q&A Section

→ Can I use raw chicken instead of cooked?

Using pre-cooked chicken is recommended for this casserole since the baking time is only 25 minutes, which isn't sufficient to cook raw chicken through completely. Rotisserie chicken, leftover grilled chicken, or poached breast meat all work perfectly.

→ How do I prevent the casserole from being watery?

Sauté the mushrooms and spinach thoroughly until they release their moisture and the liquid evaporates. This step is crucial—excess water from the vegetables can make the final dish soggy rather than creamy and cohesive.

→ Can I make this ahead of time?

Yes, assemble the entire casserole up to 24 hours in advance, cover tightly, and refrigerate. When ready to bake, you may need to add 5-10 minutes to the cooking time since it will be cold. Alternatively, bake it completely and reheat individual portions.

→ What vegetables can I substitute?

Kale or Swiss chard work well in place of spinach. Bell peppers, zucchini, or broccoli would complement the flavors nicely. Just remember to sauté any substituted vegetables thoroughly to remove excess moisture before assembling.

→ Is this freezer-friendly?

This casserole freezes well either before or after baking. If freezing unbaked, thaw completely in the refrigerator before baking as directed. For already-baked portions, wrap tightly and freeze for up to 3 months, then reheat in the oven or microwave.

→ Can I make this dairy-free?

Substitute the heavy cream with full-fat coconut cream or a dairy-free heavy cream alternative. Use vegan shredded cheese or nutritional yeast combined with a bit of olive oil for the cheesy topping. The texture will be slightly different but still satisfying.