Cheesy Keto Chicken Casserole

A simple one-dish meal, this keto chicken casserole is easy to assemble and practically bakes itself. It's the ultimate weeknight dinner!

Course Main Course

Cuisine American

Prep Time 10

Cook Time 30

Total Time 40

Servings servings

Calories 365kcal

4 boneless skinless chicken breasts 8 ounces each; 32 ounces total of raw chicken breasts
Avocado oil spray
½ teaspoon Diamond Crystal kosher salt or ¼ teaspoon of any other salt, including Morton kosher salt
¼ teaspoon black pepper

Preheat the oven to 450°F. Line a rimmed baking dish with foil and grease the foil. Arrange the chicken breasts in the prepared pan. Spray them with oil and sprinkle with salt and pepper. Bake until cooked through, for about 20 minutes.
Meanwhile, grease a 2-quart casserole dish. In a large bowl, mix the mayonnaise, sour cream, Dijon mustard, minced garlic, salt, pepper, dried thyme, paprika, cayenne, and ½ cup of shredded cheddar.
When the chicken is cooked, remove it from the oven but keep the oven on. Allow the chicken to slightly cool until it’s easier to handle. Cut it into cubes or shred it. Add the chicken cubes to the bowl with the mayonnaise-sour cream mixture and toss to coat.
Transfer the mixture to the prepared casserole dish. Sprinkle the casserole with the remaining ½ cup of shredded cheddar. Bake until the cheese is melted and the casserole is heated through, for about 10 minutes. (See notes below).
Sprinkle the casserole with sliced scallions and bacon bits. Serve immediately.

This casserole is just creamy enough for my taste, and my family likes it this way, too. However, reader feedback over the years has taught me that some people want it creamier. If you'd like your casserole to be extra creamy, I suggest you increase the mayonnaise and sour cream to ⅓ cup each.
You can season the chicken breasts with additional spices. I often add ½ teaspoon of garlic powder and ½ teaspoon of paprika.
You can replace the chicken breasts with boneless chicken thighs.
If you'd like, you can very lightly steam small broccoli florets and mix them into the casserole before the final stage of baking, making it a complete meal. If you do, I suggest you increase the mayonnaise and sour cream to ⅓ cup each.
Since I'm using warm chicken that I just cooked, I find that 10 minutes at 450°F is enough to heat the casserole through (it should reach an internal temperature of 165°F). If you plan to use cold leftover chicken, I suggest microwaving it, covered, to warm it up before adding it to the casserole. Alternatively, use the chicken cold, and bake the casserole in a preheated 400°F oven for 20-30 minutes or until heated through.
You can keep the leftovers in a sealed container in the fridge for 3-4 days. Gently reheat them, covered, in the microwave at 50% power. If you used pre-cooked chicken, take that into account when counting those 3-4 days.