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

This casserole brings together juicy chicken, tender broccoli, and savory mushrooms in a creamy, cheesy sauce that feels like comfort food without the carb crash. It’s the kind of weeknight dinner that makes the whole house smell great and leaves you with happy leftovers. The prep is simple, the ingredients are straightforward, and the results are rich and satisfying.

Whether you’re following keto or just want a cozy dinner that isn’t heavy on pasta or rice, this dish hits the spot.

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

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Prep Time 15 minutes mins

Cook Time 30 minutes mins

Total Time 45 minutes mins

Servings 6 servings

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)

Instructions

 

• Preheat and prep: Heat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with a little butter or oil.
• 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.
• 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.
• 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.
• Add cheese: Stir in 1 cup shredded cheese and the Parmesan until the sauce is creamy and thickened. Taste and adjust salt and pepper.
• Combine everything: In a large bowl, mix the chicken, broccoli, and the mushroom cream sauce until well coated.
• Assemble: Spread the mixture in the baking dish. Top with the remaining 1 cup shredded cheese.
• Bake: Bake 18–22 minutes until bubbly around the edges and the top is melted and lightly golden.
• Rest and garnish: Let it rest 5–10 minutes to set. Sprinkle with chopped parsley before serving.

What Makes This Special

This casserole nails that balance of hearty and light. You get a creamy base and melty cheese, but it’s anchored with protein and vegetables, not starch. The mushrooms add umami depth, the broccoli brings freshness and crunch, and the chicken makes it a full meal.

Plus, it’s a great use for rotisserie chicken or leftover baked chicken, making your prep even easier.

No canned soup needed: The sauce is made from scratch with cream, broth, and cheese, so you control the flavor and carbs. Meal prep-friendly: It reheats beautifully, and you can even build it ahead and bake later. Family-approved: It’s mild, creamy, and comforting—ideal for picky eaters who still need a veggie boost.

Shopping List

• 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)

Instructions

1. Preheat and prep: Heat your oven to 375°F (190°C). Grease a 9×13-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.

How to Store

• Refrigerator: Store in an airtight container for up to 4 days.

  Reheat in the oven at 325°F (165°C) until warmed through, or microwave in short bursts.

• Freezer: Cool completely, then wrap tightly. Freeze up to 2 months. Thaw overnight in the fridge and reheat covered at 350°F (175°C) until hot and bubbly.
• Make-ahead: Assemble up to 24 hours in advance, cover, and refrigerate.

  Add an extra 5–10 minutes to the bake time.

Benefits of This Recipe

• Low-carb and satisfying: Rich in protein and fat to keep you full without heavy carbs.
• Vegetable-forward: Broccoli and mushrooms add fiber, vitamins, and texture.
• Flexible: Works with leftover chicken, different cheeses, or seasonal veggies.
• Family-friendly: Creamy, cheesy, and mild enough for most palates.
• One-pan cooking (mostly): Sauce and sauté in one skillet, then bake—easy cleanup.

Pitfalls to Watch Out For

• Watery casserole: Don’t skip pre-cooking and drying the broccoli, and cook mushrooms until their liquid evaporates.
• Broken sauce: Keep heat moderate when adding cream and cheese; whisk gently for a smooth, glossy sauce.
• Overbaking: Bake just until bubbly. Overbaking can dry out the chicken and split the sauce.
• Under-seasoning: Taste the sauce before combining. Cheese adds salt, but you may still need more seasoning.

Variations You Can Try

• Bacon and scallion: Stir in 4 slices cooked, crumbled bacon and 2 sliced scallions for a smoky finish.
• Spinach and artichoke: Swap half the broccoli for fresh spinach (sauté first) and add chopped artichoke hearts.
• Buffalo-style: Add 2–3 tablespoons buffalo sauce to the cream sauce and top with blue cheese crumbles.
• Pesto twist: Stir 2 tablespoons basil pesto into the sauce and use mozzarella plus Parmesan on top.
• Different cheeses: Try Gruyère, Fontina, or smoked gouda for a deeper flavor profile.
• Dairy-light option: Use half the cheese and add an egg to the sauce to set it; still creamy, just lighter.

FAQ

Can I use raw chicken?

Yes, but cook it first.

Sauté bite-size pieces in a little oil with salt and pepper until just cooked through, then proceed with the recipe. Using cooked chicken keeps the bake time short and the texture tender.

Can I use frozen broccoli?

Absolutely. Thaw it, drain well, and press out excess moisture with paper towels.

This step helps prevent a watery casserole.

What can I substitute for heavy cream?

You can use a mix of half-and-half and extra cream cheese for thickness, though carbs will be slightly higher. Full-fat coconut milk works in a pinch, but it will add a faint coconut flavor.

Is this recipe spicy?

No, it’s mild by default. If you like heat, add a pinch of red pepper flakes or a dash of hot sauce to the sauce.

How can I add more protein?

Increase the chicken to 4 cups or add diced cooked turkey or bacon.

You can also whisk one egg into the warm sauce off the heat for extra structure and protein.

What if I don’t like mushrooms?

Skip them and add extra broccoli or substitute with diced zucchini or cauliflower florets. If using zucchini, sauté it well to drive off moisture.

How many carbs per serving?

Exact counts vary based on brands, but typically this lands around 5–7g net carbs per serving when made as written. For precise numbers, plug your ingredients into a nutrition calculator.

Can I make it in a slow cooker?

You can assemble the mixture and warm on Low for 2–3 hours, then add cheese on top to melt.

The oven method gives a better browned top and firmer texture, though.

What pan size should I use?

A 9×13-inch dish works best for even baking. An 8×11-inch dish also works; just add a few minutes if the casserole is thicker.

Final Thoughts

This Keto Chicken & Broccoli Mushroom Casserole is the kind of meal that checks all the boxes: simple to make, packed with flavor, and perfect for leftovers. It’s adaptable, budget-friendly, and reliable on busy nights.

Keep the base method handy, then switch up the cheeses and veggies to match your mood or what’s in the fridge. Comfort food doesn’t need pasta to be great—this dish proves it with every creamy, cheesy bite.