This Low-Carb Mexican Chicken Casserole puts comfort food on the low-carb table. This casserole was inspired by fajita goodness and uses up leftover chicken (or even turkey) and is loaded with spicy cheese goodness. This kid-friendly meal may be the best Mexican-inspired Chicken Casserole I’ve tried! This low-carb dinner may be part of a keto, Atkins, diabetic, or gluten-free diet.


Keto Mexican Chicken Casserole fresh from the oven.


The recipe for our Keto-Friendly, Low-Carb Mexican Chicken Casserole

This casserole has layers of spiced riced cauliflower blended with sautéed onions and green pepper, tender chicken, and a cheese sauce that will have everyone asking for more. The whole thing is topped off with more cheese then baked into bubbling goodness.


This casserole is made “from scratch”, but it’s really quite easy to make. Much of the time spent making the recipe is the time it bakes in the oven.


I based this recipe on our recipe for Low-Carb Mexican-Inspired Taco Casserole. In some ways, the two casseroles are similar. They both use riced cauliflower, a similar cheese sauce, and have that addictive gooey melted cheese on top. The biggest difference, other than the meat choice, is that this casserole has more fajita flavors–with onions and green peppers, while the taco casserole has more taco notes. Using leftover chicken in this casserole also saves a step (as well as time).


What to serve with our Low-Carb Mexican Chicken Casserole

This casserole has it all! It has the protein, veggies, and the riced cauliflower even provides a starch replacement. Because of this, you don’t really need to create a lot of side dishes. I like to serve it with a simple salad. 


If you like, you can add some salsa, additional pico de gallo, sour cream, extra cheese, or even diced jalapeños on top of the casserole. I like to put the toppings on the table separately so that everyone can customize it to their liking. 


A serving of Keto Mexican Chicken Casserole.

Disclaimer: We partner with Amazon and some of the links on this site are affiliate links which means we make a small commission from any sales to help keep the recipes coming! You do not pay any more. Thank you for your support.


How to store our keto Mexican Chicken Casserole

If you have leftovers of this casserole, you can store it in the fridge for up to three days. To store the casserole, be sure to allow it to cool completely first. 


Once the casserole has cooled, cover it tightly with a lid, reusable cover, or plastic wrap before putting in the refrigerator. 


I have not tried freezing this casserole, but I would be hesitant to try this as sometimes dairy will separate when frozen. 


How to reheat this keto-friendly Mexican Chicken Casserole

Reheating this casserole is very simple. I like to reheat this dish in the oven. To do this, preheat the oven to about 300º Fahrenheit. Remove the casserole from the refrigerator and take off the lid or cover. If the casserole is in an oven proof container, put it straight in the oven. If it is not in an oven safe container, transfer it to one before putting it in the oven.


Reheat the casserole until it is hot in the center. The time this takes will vary greatly depending on the size of the portion of casserole you’re  trying to reheat. 


Alternatively, you could reheat the casserole in the microwave. I would use 15 to 30 second increments and check the temperature after each one.


What if I don’t have leftover chicken to make the casserole?

If you don’t have leftover chicken, you have many options! You could use leftover turkey, if you happen to have some on hand. This casserole is a great way to use up that leftover Thanksgiving turkey!


You could also use rotisserie chicken from the grocery store. Simply pick off enough for the recipe and use the rest for a different purpose.


Another option is to cook fresh chicken specifically for this recipe. To do this, cut some chicken breasts or tenders into 1/2 cubes (a pound of ground chicken or turkey would also work) and sprinkle lightly with salt and pepper (if desired).


Heat a large skillet over medium heat. When the skillet is hot, add a tablespoon or so of avocado oil. Next, add the chicken. Cook chicken, stirring occasionally until the outside starts to brown and the cubes are cooked through. Transfer the cooked chicken to a plate and set aside.


Once the chicken is cooked, you can use the same skillet to cook the onions and peppers without even washing it. The chicken goodness in the pan will had some extra flavor to the casserole. 


Keto Mexican Chicken Casserole--taking a bite.


What are some other keto-friendly ways to use up leftover chicken?

Some may have the opposite problem of no leftover chicken and have too much. This might happen if you purchase a rotisserie chicken to use for this recipe. The good news is that there are lots of different ways to use up leftover chicken. 


Leftover chicken can be used in most recipes for leftover turkey. For example, it would be perfect in our Low-Carb Leftover Turkey (or Chicken) Avocado SaladLow-Carb Leftover Turkey Casserole, or our Leftover Turkey (or Chicken) Soup.


This round-up from Traditional Cooking School has some wonderful ideas as well. Of course, you can always simply reheat the chicken to enjoy a simple main course of chicken.

Final words 

This casserole makes a wonderful way to use up leftover chicken, but it’s also a great way to satisfy that craving for Mexican food without going over your carb macros. Enjoy!


Low-Carb Mexican Chicken Casserole

This Low-Carb Mexican-Inspired Chicken Casserole puts comfort food on the low-carb table. This casserole uses up leftover chicken (or even turkey) and is loaded with spicy cheese goodness. Keto-friendly and gluten-free.


Keto Mexican Chicken Casserole before serving.
4.5 from 4 votes

Low-Carb Mexican Chicken Casserole

This Low-Carb Mexican Chicken Casserole puts comfort food on the low-carb table. This casserole uses up leftover chicken (or even turkey) and is loaded with spicy cheese goodness. This kid-friendly meal may be the best Mexican Chicken Casserole I've tried! This low-carb dinner may be part of a keto, Atkins, diabetic, or gluten-free diet.

Course Main Course
Cuisine low-carb, Mexican
Keyword family friendly keto recipe, keto chicken recipe, Keto Mexican Chicken bake, keto Mexican Chicken Casserole, keto mexican food, Kid-friendly keto recipe, low carb casserole
Prep Time 20 minutes
Cook Time 35 minutes
Total Time 55 minutes
Servings 6
Calories 393 kcal
Author Annissa Slusher


  • 1 spray coconut oil
  • 1 tablespoon avocado oil
  • 1 small onion ( 2-3 ounces) peeled and sliced lengthwise
  • ½ medium green pepper seeds and ribs removed, diced
  • 20 ounces riced cauliflower frozen or fresh
  • 1 teaspoon chili powder
  • ½ teaspoon cumin
  • ¼ teaspoon dried oregano
  • ¼ to ½ teaspoon sea salt optional
  • teaspoon black pepper freshly ground
  • 1 clove garlic crushed
  • 6 ounces cheddar cheese shredded
  • 1 cup heavy whipping cream
  • 1/2 cup pico de gallo fresh
  • sea salt to taste
  • black pepper freshly ground, to taste
  • 2 cups leftover chicken chopped
  • 1 tablespoon fresh cilantro chopped


  1. Preheat oven to 350º Fahrenheit. Grease an 8" x 8" baking dish or similar size casserole with butter or coconut oil. 

    Low-Carb Mexican Taco Casserole-spraying the dish.
  2. Preheat a large skillet over medium high heat. Add the avocado oil. When oil is hot, add the onion and pepper. Cook, stirring occasionally, until almost tender and edges have begun to brown.

    Browning the onions and pepper.
  3. Stir in riced cauliflower, chill powder, cumin, dried oregano, sea salt, and black pepper. Cook until the cauliflower is tender and any water released from the cauliflower has evaporated. Stir in garlic and cook for about one minute. Taste and adjust seasoning if desired.

    Adding the spices to the Mexican Chicken Casserole.
  4. Spread about ⅓rd of the mixture in the prepared baking dish. Evenly distribute about half of the chicken over the cauliflower mixture.

    Starting the layers of the casserole.
  5. Repeat for the second ⅓rd of the cauliflower mixture and the second half of the chicken. Top with the last third of the cauliflower mixture.

    Casserole after layering is complete.
  6. Pour the cream into a  1 1/2 quart heavy saucepan. Add 4 ounces (about 1 cup packed) of the grated cheese (this leaves 2 ounces for later). Put saucepan over medium-low heat. Heat cream and cheese, stirring frequently, until cheese has melted. Stir in the salsa (pico de Gallo) a little at a time. Bring mixture to a simmer and simmer gently, while whisking, until mixture has thickened. 

    Adding the pico de gallo to the cheese sauce.
  7. Taste sauce and add sea salt and black pepper if desired. Pour sauce over the contents of the baking dish. Top with the remaining ounce of cheese.

    Casserole has cheese sauce and cheese on top.
  8. Bake in the preheated oven for 35-40 minutes, or until cheese has melted and contents are bubbly in the center. Sprinkle chopped cilantro on top to garnish. 

    Baked casserole with cilantro on top.
Nutrition Facts
Low-Carb Mexican Chicken Casserole
Amount Per Serving
Calories 393 Calories from Fat 279
% Daily Value*
Fat 31g48%
Saturated Fat 15g94%
Trans Fat 0g
Polyunsaturated Fat 1g
Monounsaturated Fat 4g
Cholesterol 91mg30%
Sodium 362mg16%
Potassium 305mg9%
Carbohydrates 8g3%
Fiber 3g13%
Sugar 3g3%
Protein 22g44%
Vitamin A 98%2%
Vitamin C 59%72%
Calcium 208%21%
Iron 8%44%
Net Carbs 5g
* Percent Daily Values are based on a 2000 calorie diet.