Name: Keto Garlic Mushroom Chicken Casserole Recipe
Prep time: 15 min
Cook time: 30 min
Total time: 45 min
Ingredients: 2 pounds boneless skinless chicken thighs, cut into bite-size pieces; 2 tablespoons olive oil or avocado oil; 3 tablespoons butter or ghee, divided; 16 ounces cremini or baby bella mushrooms, sliced; 4 cloves fresh garlic, minced; 1 cup chicken broth, low sodium; 4 ounces cream cheese, softened and cubed; 1 cup heavy whipping cream; 1 1/2 cups shredded mozzarella cheese; 1/2 cup grated parmesan cheese; 1 1/2 teaspoons sea salt or kosher salt, divided, plus more to taste; 1 teaspoon black pepper, divided; 1 teaspoon smoked paprika or regular paprika; 1 teaspoon dried thyme or Italian seasoning, plus more to taste; 1/2 teaspoon onion powder; 1/4 teaspoon red pepper flakes; 2 tablespoons chopped fresh parsley or chives, for garnish

Keto Garlic Mushroom Chicken Casserole Recipe tastes rich, creamy, and garlicky with juicy chicken, tender mushrooms, and a cheesy golden top. It works perfectly for busy low carb eaters who want a comfort food dinner on the table in about 45 minutes. I first tested this on a chaotic Tuesday with kids arguing over broccoli, and this casserole shut everyone up in the best way.

Why Make This Keto Garlic Mushroom Chicken Casserole Recipe at Home

You control every ingredient, so the casserole stays low carb, gluten free, and free of mystery thickeners. Restaurants often sneak in flour, sugar, or cornstarch, while this version uses cream, cheese, and mushrooms to build flavor and texture.

You also get a full one-pan style dinner that reheats well and works for meal prep. The garlic and mushroom flavor deepens overnight, so leftovers taste even better the next day.

My whole family devoured this Keto Garlic Mushroom Chicken Casserole Recipe and fought over the crispy cheesy edges. ★★★★★

Ingredients You Need

Main ingredients

Chicken thighs, boneless and skinless
- Use thighs for juicy, forgiving meat that stays tender.
- You can use chicken breast if you prefer, but watch the cooking time so it does not dry out.
Mushrooms, sliced
- Cremini or baby bella mushrooms bring deeper flavor than plain white mushrooms.
- Use pre-sliced mushrooms from the store as a time saver.
Fresh garlic, minced
- Fresh cloves give the best flavor.
- Use jarred minced garlic in water or oil when you need a shortcut, but double check carb counts on the label.
Heavy whipping cream
- This gives the casserole a rich, creamy sauce without flour.
- Do not swap with regular milk, which adds carbs and makes the sauce thin.
Cream cheese, softened
- Adds body and tang to the sauce.
- I often use Philadelphia brand because it melts smoothly, but any full-fat brick cream cheese works.
Shredded mozzarella cheese
- Melts stretchy and gooey on top.
- Buy a block and shred it yourself when possible, since bagged shreds sometimes include starch.
Grated parmesan cheese
- Adds salty, nutty flavor and helps brown the top.
- Use real parmesan, not the powdery shaker kind, for best taste.
Butter or ghee
- Butter browns the mushrooms and garlic and adds richness.
- Use ghee if you need to avoid lactose.
Olive oil or avocado oil
- Helps sear the chicken without burning the butter.
- Avocado oil handles higher heat slightly better.
Chicken broth
- Adds savory flavor and thins the sauce to the right consistency.
- Use low sodium broth so you control the salt level.

Seasonings

Sea salt or kosher salt
Black pepper
Onion powder
Dried thyme or Italian seasoning
Smoked paprika or regular paprika
Optional: red pepper flakes for a little heat
Optional: fresh parsley or chives for garnish

Substitutions and low carb tweaks

Swap cream cheese with mascarpone for a milder, silkier sauce.
Use rotisserie chicken (no sugary rub) to save time; shred it and skip the raw chicken searing step.
Replace some mushrooms with chopped zucchini or spinach to sneak in extra low carb veggies.
Use lactose free cream and cheese alternatives if you tolerate them and want a lighter dairy load.

Equipment list

Large oven-safe skillet or sauté pan
- A 10 to 12 inch cast iron or stainless skillet works best so you go from stove to oven.
Cutting board and sharp knife
Garlic press or small knife for mincing
Measuring cups and spoons
Mixing spoon or spatula
9×13 inch baking dish if your skillet cannot go in the oven
Aluminum foil to tent the top if it browns too quickly

Tips & Mistakes

Brown the chicken pieces in a single layer so they sear and caramelize instead of steaming.
Pat the chicken dry with paper towels, or the moisture will fight against browning.
Slice mushrooms evenly so they cook at the same rate and do not turn soggy.
Cook mushrooms until they release liquid and that liquid mostly cooks off, or the sauce will taste watery.
Use room temperature cream cheese so it melts into the sauce without clumps.
Add heavy cream on low to medium heat and stir often, since high heat can cause it to separate.
Taste the sauce before baking and adjust salt and pepper, because cheese and broth salt levels vary.
Do not drown the casserole in sauce; aim for everything coated with a little extra, not swimming.
Shred cheese from a block when possible, since some pre-shredded cheese melts in clumps.
Let the casserole rest 5 to 10 minutes after baking so the sauce thickens and slices hold together.
Avoid overbaking, which dries out chicken and makes the cheese rubbery; pull it when the center bubbles and cheese turns golden.
Keep the garlic fragrant and pale; if it turns dark brown, it tastes bitter and overpowers the dish.

How to Make Keto Garlic Mushroom Chicken Casserole Recipe

Step 1: Prep the ingredients

Chop the chicken thighs into bite-size pieces or strips and pat them dry. Season generously with salt, pepper, paprika, and a pinch of thyme or Italian seasoning. Slice mushrooms, mince garlic, and cube the cream cheese so it melts faster.

Step 2: Sear the chicken

Heat a mix of olive oil and butter in a large skillet over medium high heat. Add the seasoned chicken in a single layer and sear each side until golden and mostly cooked through, about 3 to 4 minutes per side. Transfer the chicken to a plate and keep any browned bits in the pan, since those bits carry flavor.

Step 3: Cook the mushrooms and garlic

Lower the heat to medium and add a little more butter if the pan looks dry. Add the sliced mushrooms and cook, stirring occasionally, until they soften and release their liquid, then keep cooking until most of the liquid cooks off and the mushrooms start to brown. Stir in the minced garlic and cook about 30 to 60 seconds until fragrant, not dark.

Step 4: Build the creamy low carb sauce

Pour in the chicken broth and scrape the bottom of the pan to lift up the browned bits. Add the cream cheese cubes and stir until they melt into the broth and coat the mushrooms. Pour in the heavy cream, sprinkle in onion powder and more thyme or Italian seasoning, then simmer on low heat until the sauce thickens slightly and coats the back of a spoon.

Step 5: Combine chicken and sauce

Return the seared chicken and any juices from the plate to the skillet. Stir so every piece of chicken nestles into the garlic mushroom cream sauce. Taste and adjust salt, pepper, and red pepper flakes if you like a little kick.

Step 6: Add cheese and transfer to baking dish if needed

If your skillet can go in the oven, keep everything in that pan. If not, pour the chicken and sauce into a greased 9×13 inch baking dish. Sprinkle shredded mozzarella evenly over the top, then add grated parmesan for extra browning.

Step 7: Bake until bubbly and golden

Place the skillet or baking dish in a preheated 375°F oven. Bake about 15 to 20 minutes until the casserole bubbles around the edges and the cheese turns golden in spots. If the top browns too quickly, tent loosely with foil and keep baking until the center heats through.

Step 8: Rest and garnish

Remove the Keto Garlic Mushroom Chicken Casserole Recipe from the oven and let it rest 5 to 10 minutes. This short rest helps the sauce thicken and keeps portions from sliding all over the plate. Sprinkle chopped parsley or chives on top for a fresh pop of color and flavor.

Variations I've Tried

I sometimes add a handful of fresh spinach or kale to the mushroom mixture near the end of cooking, which wilts into the sauce and adds extra greens without many carbs. Another favorite twist uses a mix of mushrooms like shiitake and oyster for deeper umami flavor. I also swap mozzarella with a blend of provolone and fontina when I want a slightly sharper, more grown up cheese vibe.

You can turn this into a full one-pan meal by adding small broccoli florets or cauliflower rice to the skillet before baking. I also tried a version with a little cooked bacon crumbled over the top before baking, which gave a smoky, salty crunch that low carb friends loved.

How to Serve Keto Garlic Mushroom Chicken Casserole Recipe

Spoon generous portions over steamed or roasted broccoli, cauliflower rice, or sautéed green beans for a fully low carb plate. You can also serve it with a simple side salad with crisp lettuce, cucumber, and a creamy ranch or Caesar style dressing. Kids often enjoy it with plain buttered cauliflower mash that soaks up the sauce.

This casserole also works well as a meal prep lunch; pack it with a side of sliced cucumbers or bell peppers for crunch. If you host guests who do not follow keto, they can enjoy it with garlic bread or regular rice while you keep your plate low carb.

How to store

Cool leftovers to room temperature within about 30 minutes, then store in airtight containers in the fridge for up to 3 to 4 days.
Freeze portions in freezer safe containers for up to 2 to 3 months, and label with the date so you track freshness.
Reheat in the oven at 325°F, covered, until hot and bubbly, then uncover for a few minutes to refresh the cheese top.
For quick single servings, reheat gently in the microwave at 50 to 70 percent power, stirring halfway so the sauce heats evenly and does not separate.