Keto Garlic Mushroom Chicken Casserole

The Keto Garlic Mushroom Chicken Casserole is a creamy, comforting bake made with tender chicken, sautéed mushrooms, fresh garlic, heavy cream, and melty cheese. By skipping flour, milk, and breadcrumbs, this low-carb casserole keeps the focus on rich, garlicky flavor and a naturally thick, velvety sauce. Sautéing the mushrooms first removes excess moisture, while a brief simmer of the cream and cheese creates a luscious, spoon-coating consistency. With plenty of fat and protein and only a few net carbs per serving, it is ideal for busy weeknights, meal prep, or feeding a crowd. It reheats beautifully and pairs perfectly with a simple green salad for a complete keto-friendly meal.

Course Casserole, Dinner, Main Course

Cuisine American, Keto, Low Carb

Keyword baked chicken with cream sauce, garlic mushroom chicken, gluten free, keto chicken casserole, low carb casserole

Prep Time 15

Cook Time 35

Total Time 50

Servings servings

Calories 520kcal

Equipment

9x13-inch Baking Dish
large skillet
Cutting board
Chef's knife
Mixing bowl
Tongs

Ingredients

For the chicken and mushrooms

2 pounds boneless skinless chicken breasts cut into 1-inch pieces
1 teaspoon fine sea salt for seasoning chicken
0.5 teaspoon black pepper for seasoning chicken
2 tablespoons olive oil
2 tablespoons unsalted butter
16 ounces cremini or white mushrooms sliced
6 cloves garlic minced

For the creamy garlic sauce

1.5 cups heavy cream
4 ounces cream cheese cut into small cubes and softened
0.5 cup chicken broth low sodium, no sugar added
1 teaspoon dried thyme or 2 teaspoons fresh thyme leaves
0.5 teaspoon onion powder
0.25 teaspoon fine sea salt to taste for the sauce
0.25 teaspoon black pepper to taste for the sauce

For the cheese topping and garnish

1.5 cups shredded mozzarella cheese low moisture, part-skim
0.5 cup shredded sharp cheddar cheese
2 tablespoons fresh parsley chopped, for garnish

Instructions

Preheat the oven to 375°F and lightly grease a 9x13 inch baking dish.
Pat the chicken pieces dry with paper towels, season them evenly with the teaspoon of salt and the half teaspoon of pepper, and set aside.
Heat the olive oil and butter in a large skillet over medium high heat until the butter is melted and foamy.
Add the sliced mushrooms to the skillet and cook, stirring occasionally, until they release their moisture and turn deep golden and most of the liquid has evaporated, about 7 to 8 minutes.
Stir in the minced garlic and cook until fragrant, about 30 seconds, then transfer the mushroom mixture to the prepared baking dish and spread it in an even layer.
In the same skillet over medium heat, add the seasoned chicken pieces and sear until the outside is opaque and lightly golden but not fully cooked through, about 4 to 5 minutes, then transfer the chicken to the baking dish and distribute it over the mushrooms.
Reduce the skillet heat to medium low, pour in the chicken broth and heavy cream, and add the cream cheese cubes, thyme, onion powder, salt, and pepper, stirring gently as the cream cheese melts.
Simmer the sauce, stirring frequently, until the cream cheese is completely smooth and the sauce has thickened enough to coat the back of a spoon, about 3 to 5 minutes, then taste and adjust seasoning if needed.
Pour the hot creamy garlic sauce evenly over the chicken and mushrooms in the baking dish, gently nudging with a spatula so the sauce seeps down between the pieces.
Sprinkle the shredded mozzarella and cheddar cheeses evenly over the top of the casserole.
Bake the casserole uncovered until the chicken is cooked through to an internal temperature of 165°F and the sauce is bubbling around the edges, about 18 to 22 minutes.
Turn the oven to broil on high and broil the casserole for 2 to 3 minutes, watching closely, until the cheese is golden and slightly browned in spots.
Remove the casserole from the oven and let it rest for 5 to 10 minutes to thicken slightly before serving.
Sprinkle the hot casserole with chopped fresh parsley and serve warm, optionally with a crisp green salad on the side for a complete keto meal.

Notes

For extra richness you can substitute half of the chicken breasts with boneless skinless chicken thighs, which stay very tender in the oven. If you prefer a stronger herb flavor, increase the thyme or add a pinch of rosemary, but avoid premade seasoning blends that may contain added sugars or starches. The casserole can be assembled a day ahead through the step of pouring on the sauce; cover tightly and refrigerate, then top with cheese just before baking, adding a few extra minutes to account for the cold dish. Leftovers keep well in an airtight container in the refrigerator for up to 4 days and can be reheated in a 300°F oven covered with foil until warmed through, or in the microwave in short bursts, stirring between bursts to maintain the creamy texture. Each serving is very filling, so pair it with low carb sides like a simple green salad, roasted broccoli, or sautéed spinach to keep the meal strictly keto.

Nutrition