Keto Garlic Mushroom Chicken Casserole (Creamy, Low-Carb & One Pan)

This Keto Garlic Mushroom Chicken Casserole is the kind of comforting, hearty meal you’ll want to make again and again. Juicy chicken thighs, golden sautéed mushrooms, and tender spinach are enveloped in a rich, garlicky cream sauce—then baked until bubbly and golden. It’s low in carbs, high in protein and fat, and absolutely packed with flavor.

This is an ideal weeknight dinner or make-ahead meal that works just as well for family dinners as it does for keto meal prep. Plus, it’s a true one-pan wonder—easy cleanup included.

Why You’ll Love This Casserole

This dish is the keto trifecta: creamy, savory, and ultra-satisfying. It’s:

Low-carb and keto-friendly
Naturally gluten-free
Loaded with protein and healthy fats
All made in one skillet or baking dish
Easy to prep and even easier to love

This casserole checks all the boxes—comfort food meets smart macros.

Ingredient Overview: What You’ll Need

Chicken Thighs or Breasts (Boneless, Skinless)

Thighs stay juicy and flavorful during baking.
Breasts work well too—just don’t overcook.
Sear for added flavor before baking.

Mushrooms (Cremini or White Button)

Add meaty texture and umami depth.
Sauté until golden for maximum flavor.

Garlic (Fresh, Minced)

Essential for the sauce—adds aromatic depth.
Use 3–4 cloves for a bold garlic kick.

Spinach (Fresh or Frozen)

Adds nutrients, fiber, and color.
Wilt it into the sauce before baking.

Heavy Cream

The keto base of your creamy sauce.
Rich, indulgent, and perfect for low-carb cooking.

Cream Cheese

Thickens the sauce and adds velvety richness.

Parmesan Cheese (Freshly Grated)

Salty, nutty flavor that melts beautifully.
Helps thicken the sauce and creates a cheesy top layer.

Mozzarella (Optional for Topping)

Optional for a stretchy, golden topping.
Adds indulgence, especially for cheese lovers.

Olive Oil or Butter

For sautéing the mushrooms and garlic.

Seasonings

Salt and black pepper
Dried thyme or Italian seasoning for an herbaceous note
Crushed red pepper flakes (optional for a bit of heat)

Step-by-Step Instructions

Step 1: Preheat & Prep

Preheat oven to 375°F (190°C).
Lightly grease a 9×13 casserole dish or use an oven-safe skillet.

Step 2: Sear the Chicken

Heat 1 tbsp olive oil in a large skillet over medium-high heat.
Season 1.5–2 lbs of chicken thighs with salt, pepper, and herbs.
Sear chicken for 3–4 minutes per side until golden (does not need to be cooked through).
Remove and set aside.

Step 3: Sauté the Mushrooms & Garlic

In the same pan, add 1 more tbsp oil or butter.
Add 8 oz sliced mushrooms and cook until golden, about 5–6 minutes.
Stir in 3–4 cloves minced garlic and cook for 1 minute.

Step 4: Make the Sauce

Lower heat and add:
- ¾ cup heavy cream
- 4 oz cream cheese, cut into chunks
- ½ cup grated Parmesan cheese
- ½ tsp salt, ¼ tsp black pepper
- Optional: ½ tsp dried thyme or Italian seasoning
Stir until smooth and creamy.

Step 5: Add Spinach

Add 2 cups fresh spinach and stir until wilted (or add thawed, drained frozen spinach).

Step 6: Assemble and Bake

Return the chicken to the pan, nestling into the sauce.
If using a casserole dish, pour sauce and veggies into dish, then top with chicken.
Sprinkle with ½ cup shredded mozzarella (optional).

Bake for 20–25 minutes, or until chicken reaches 165°F and sauce is bubbly and thick.

Step 7: Rest & Serve

Let rest for 5 minutes before serving.
Garnish with chopped parsley, more Parmesan, or red pepper flakes.

Tips, Variations & Substitutions

Pro Tips:

Pre-searing the chicken adds flavor but can be skipped if using shredded rotisserie chicken.
Thicker sauce? Simmer longer or add extra cream cheese or Parmesan.
Don’t overbake—it’ll dry out the chicken.

Flavor Variations:

Add bacon: Crumbled cooked bacon takes this over the top.
Keto Tuscan-style: Add sun-dried tomatoes and basil.
Herb boost: Try rosemary or sage for a deeper savory note.

Substitutions:

Cream cheese → Mascarpone or sour cream
Parmesan → Asiago or Pecorino Romano
Spinach → Kale or Swiss chard
Chicken → Turkey, pork chops, or firm tofu (for low-carb vegetarian)

Serving Ideas & Occasions

What to Serve With:

Cauliflower mash or cauliflower rice
Zucchini noodles or keto pasta
Steamed green beans, broccoli, or asparagus
Crisp side salad with vinaigrette

Great For:

Weeknight keto dinners
Family comfort food night
Meal prep (store in portions!)
Holiday table for low-carb guests

Nutritional & Health Notes

This casserole is:

Keto-friendly (approx. 5–7g net carbs per serving)
Gluten-free
High in protein (25–30g per serving)
Rich in calcium and vitamin D from the dairy

Using chicken thighs boosts satiety, while mushrooms and spinach add micronutrients like selenium, B vitamins, and iron.

Approximate per serving (1/6 of recipe):

Calories: 400–450
Net Carbs: 5–7g
Protein: 30g
Fat: 30g+

FAQ: Keto Garlic Mushroom Chicken Casserole

1. Can I make this ahead of time?

Yes! Assemble the entire dish, cover, and refrigerate for up to 24 hours. Bake when ready. Or, bake fully and reheat gently.

2. Can I freeze leftovers?

Absolutely. Cool completely, then store in airtight freezer containers for up to 2 months. Thaw overnight and reheat in oven or microwave.

3. What type of mushrooms work best?

Cremini, baby bella, or white button mushrooms all work. You can even use a mix with shiitake or portobello for depth.

4. Can I use cooked chicken?

Yes. Shredded rotisserie chicken is a great shortcut. Just stir it into the sauce before baking.

5. Is this casserole good for keto macros?

Yes! It’s high in fat and protein with low carbs—perfect for ketogenic and low-carb diets.

6. How can I thicken the sauce more?

Add more cream cheese or simmer longer before baking. You can also stir in grated mozzarella before baking to make it thicker.

7. Can I make it dairy-free?

You can try using coconut cream instead of dairy and dairy-free cheese alternatives, but the texture and taste will change significantly.