This oven-baked casserole features tender chicken thighs topped with a savory layer of sautéed mushrooms and minced garlic in a thick, velvety cream sauce. Finished with a blend of melted mozzarella and Parmesan, the dish develops a golden, bubbling surface that contrasts with the earthy, umami-rich flavors of the mushrooms. It is a hearty and aromatic meal that highlights the classic combination of garlic, thyme, and cream.

About This Recipe

The kitchen fills with the deep, savory scent of browning mushrooms and garlic as this casserole simmers in the oven. The mushrooms are first sautéed to concentrate their flavor and ensure they retain a firm texture within the rich sauce. Each chicken thigh is coated in a smooth glaze of heavy cream and dried thyme, which reduces into a thick, savory gravy that pools around the base of the dish.

The earthy flavor of the mushrooms pairs with the sharp aroma of the minced garlic, creating a bold, savory base. The heavy cream adds a luxurious sweetness that mellows the garlic, while the addition of Parmesan provides a salty, sharp finish to the melted cheese crust. As the chicken juices meld with the cream and seasonings, the sauce develops a glossy consistency that clings to every ingredient.

This dish is typically served warm and bubbling, showcasing the stretchy texture of the mozzarella against the tender meat. It is a visually appealing meal, with the dark, golden-brown mushrooms peeking through a layer of toasted cheese. The balance of creamy dairy, savory poultry, and bold aromatics makes it well suited for a centerpiece dinner on a cold evening.

Why You’ll Love This Recipe

Deep garlic and mushroom flavor
Creamy sauce without flour or starch
Oven-baked and low effort
Chicken stays tender and juicy
Classic comfort-style casserole
Reheats well without separating
Easy to pair with low-carb sides

What You’ll Need for This Keto Garlic Mushroom Chicken Casserole

2 lb boneless, skinless chicken thighs
12 oz mushrooms, sliced
1 ¼ cups heavy cream
4 cloves garlic, minced
1 tsp onion powder
1 tsp dried thyme
¾ tsp salt
½ tsp black pepper
½ cup shredded mozzarella cheese
¼ cup grated Parmesan cheese
2 tbsp butter
1 tbsp olive oil

Step-by-Step Preparation

Preheat the oven to 375°F and lightly grease a baking dish.
Heat olive oil and butter in a skillet over medium heat. Add mushrooms and cook until browned and most moisture has evaporated.
Add minced garlic to the mushrooms and cook for 30 seconds until fragrant. Remove from heat.
Arrange the chicken thighs evenly in the prepared baking dish.
Spread the mushroom and garlic mixture over the chicken.
In a bowl, whisk together heavy cream, onion powder, dried thyme, salt, and black pepper.
Pour the cream mixture evenly over the chicken and mushrooms.
Sprinkle mozzarella and Parmesan evenly on top.
Bake uncovered for 40–45 minutes, until the chicken is cooked through and the sauce is thick and bubbling.
Rest for 5 minutes before serving.

FAQ

Can I use chicken breasts instead of thighs?
Yes, but thighs stay juicier and are more forgiving during baking.
Will the mushrooms release too much liquid?
Not if they are sautéed properly before baking.
Does this casserole thicken without flour?
Yes, the cream reduces naturally and the cheese stabilizes the sauce.
Can this be made ahead of time?
Yes, assemble in advance and bake when ready.
Is this freezer-friendly?
It can be frozen, though the sauce may slightly soften when reheated.

Variations & Substitutions

Add spinach for extra color and texture
Use Swiss cheese instead of mozzarella
Swap thyme for rosemary
Add cooked bacon for extra richness
Finish with fresh parsley if desired

Serving Suggestions

Serve with roasted cauliflower
Pair with sautéed zucchini
Add a simple leafy green salad

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