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Keto Chicken & Broccoli Mushroom Casserole – Creamy, Comforting, and Low-Carb

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Prep Time 15 minutes
Cook Time 30 minutes
Total Time 45 minutes
Servings: 6 servings
Ingredients Method

Ingredients
  

  • Chicken: 3 cups cooked chicken, shredded or cubed (rotisserie works great)
  • Broccoli: 4 cups small florets (fresh or frozen)
  • Mushrooms: 8 ounces cremini or button mushrooms, sliced
  • Onion: 1/2 medium yellow onion, finely chopped
  • Garlic: 3 cloves, minced
  • Butter or avocado oil: 2 tablespoons
  • Heavy cream: 1 cup
  • Chicken broth: 1/2 cup (low-sodium)
  • Cream cheese: 4 ounces, softened
  • Shredded cheese: 2 cups total (1 cup mozzarella for melt, 1 cup sharp cheddar or Gruyère for flavor)
  • Parmesan: 1/4 cup grated (optional but delicious)
  • Seasonings: 1 teaspoon salt, 1/2 teaspoon black pepper, 1 teaspoon onion powder, 1 teaspoon garlic powder
  • Herbs: 1 teaspoon dried thyme or Italian seasoning
  • Mustard: 1 teaspoon Dijon (optional, for depth)
  • Crushed red pepper flakes: Pinch (optional)
  • Fresh parsley: For garnish (optional)

Method
 

  1. Preheat and prep: Heat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with a little butter or oil.
  2. Par-cook the broccoli: Steam or microwave the florets until crisp-tender, about 2–3 minutes. Drain well and pat dry to avoid a watery casserole.
  3. Sauté the mushrooms and aromatics: In a large skillet over medium heat, melt the butter. Add onions and cook 3 minutes until softened. Add mushrooms and a pinch of salt; cook 5–6 minutes until browned and most liquid evaporates. Stir in garlic for 30 seconds.
  4. Make the sauce: Reduce heat to low. Add cream cheese to the skillet and stir until melty. Pour in heavy cream and chicken broth, whisking until smooth. Stir in Dijon, onion powder, garlic powder, thyme, salt, pepper, and red pepper flakes if using.
  5. Add cheese: Stir in 1 cup shredded cheese and the Parmesan until the sauce is creamy and thickened. Taste and adjust salt and pepper.
  6. Combine everything: In a large bowl, mix the chicken, broccoli, and the mushroom cream sauce until well coated.
  7. Assemble: Spread the mixture in the baking dish. Top with the remaining 1 cup shredded cheese.
  8. Bake: Bake 18–22 minutes until bubbly around the edges and the top is melted and lightly golden.
  9. Rest and garnish: Let it rest 5–10 minutes to set. Sprinkle with chopped parsley before serving.