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Easy Keto Fajita Casserole Recipe

A comforting and healthy one-pan Keto Fajita Casserole packed with tender chicken, colorful bell peppers, and zesty spices, perfect for weeknight dinners or meal prep.

By Shary Eliot ·MAR 19, 2026 ·Updated SEP 25, 2026 ·Be the first to rate
Easy Keto Fajita Casserole Recipe
01Why this one

Indulge in a Flavorful Keto Fajita Casserole

If you’re searching for a comforting yet healthy recipe that satisfies your cravings, look no further than this Keto Fajita Casserole. This dish combines tender chicken, colorful bell peppers, and zesty spices, bringing a burst of flavor to your table. Perfect for weeknight dinners or meal prep, it’s a great addition to your keto diet.

Why make this recipe

This recipe isn’t just delicious; it brings numerous benefits that make it a standout choice for any meal occasion. First, it’s a one-pan dish, simplifying cleanup and minimizing the hassle in the kitchen. Additionally, it’s quick to prepare, taking only about 30 minutes from start to finish, which is a fantastic option for busy evenings.

Not to mention, it’s healthy, low in carbs, and adaptable to various dietary preferences. You can easily tweak the spice levels or substitute ingredients, ensuring everyone at the table finds it satisfying. For more keto chicken inspiration, check out this collection of keto chicken recipes.

02Before you cook

The cooking process explained

Let’s dive into how to prepare this delightful casserole. This overview sets you up for success by breaking down the process, so you understand what to expect.

  1. Prep your ingredients: Ensure your chicken, vegetables, and spices are ready to go.
  2. Cook the chicken: You’ll start by browning the chicken strips in olive oil.
  3. Add spices: After the chicken is golden, introduce the spices to enhance the flavor.
  4. Caramelize the onions and peppers: This step adds depth and sweetness to the dish.
  5. Combine everything: Mix in the cooked chicken, pour in the tomato passata, and bake until bubbly.

What you’ll need

Gather the following ingredients to create this savory dish:

  • Olive oil: 2 tablespoons (30 ml) + optional 1 tablespoon
  • Chicken breasts: 320 grams (11.3 oz), cut into strips
  • Onion: 180 grams (6.3 oz), cut into thin strips
  • Yellow or green pepper: 80 grams (2.8 oz), cut into strips
  • Red pepper: 80 grams (2.8 oz), cut into strips
  • Salt: 1 teaspoon (5 grams), or more to taste
  • Ground pepper: ¼ teaspoon (1 gram)
  • Powdered garlic: ¼ teaspoon (1 gram)
  • Cumin: ¼ teaspoon (1 gram)
  • Oregano: ½ teaspoon (2 grams)
  • Paprika: 1 teaspoon (5 grams)
  • Tomato passata: 2 tablespoons (30 grams)
  • Water: 200 ml (6.8 fl oz)
  • Shredded cheese (mozzarella or cheddar): 1 cup (100 grams / 3.5 oz)

Feel free to use different colored peppers to make the dish even more visually appealing!

03At the stove

Step-by-step instructions

  1. In a large skillet, heat 2 tablespoons of olive oil over medium-high heat.
  2. Add the chicken strips to the hot oil and cook until golden brown on the edges.
  3. Season the chicken with salt, ground pepper, powdered garlic, cumin, oregano, and paprika. Stir for about 20 seconds, letting the spices toast.
  4. Transfer the cooked chicken to a plate and set aside.
  5. In the same skillet, add 1 more tablespoon of olive oil and 1 tablespoon of water.
  6. Add the onion strips and cook until they’re caramelized and golden brown.
  7. If needed, add more water to prevent sticking.
  8. Add in the yellow/green and red pepper strips, stirring until they are golden brown.
  9. Return the cooked chicken to the skillet with the vegetables, adjusting seasoning if desired.
  10. Pour in the tomato passata and 200 ml of water, stirring to blend.
  11. Sprinkle the shredded cheese evenly over the top.
  12. Transfer to a preheated oven at 190°C (374°F) and bake for about 10 minutes, or until the cheese is melted and bubbly.
  13. Serve over Greek yogurt, cottage cheese, cauliflower rice, or in keto taco shells.
Keto Fajita Casserole
The recipe

Keto Fajita Casserole

Rate it ·Dinner · Main Course · Keto · Mexican
Prep
10 MIN
Cook
20 MIN
Total
30 MIN
Serves
4

01Ingredients

4 servings

Main Ingredients

Spices

02Method

  1. Preparation
  2. Cooking
  3. Serving

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03Recipe notes

  1. 01Tip: For a creamier texture, you can mix in some cream cheese along with the tomato passata. This casserole can also be adapted for vegetarian diets by substituting chicken with chickpeas or vegetables. Store leftovers in an airtight container.
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04After dinner

Best ways to enjoy it

This Keto Fajita Casserole is incredibly versatile when it comes to servings! You can enjoy it on its own, or pair it with sides like a fresh green salad or cauliflower rice for a complete meal. Another fun idea is to use it as a filling for lettuce wraps or keto taco shells, presenting a delightful twist on traditional fajitas.

Keeping leftovers fresh

To store your casserole, let it cool completely before placing it in an airtight container. You can keep it in the refrigerator for up to 3 days. Reheating can be done in the microwave or oven. If you wish to freeze the casserole, ensure it’s well wrapped to prevent freezer burn; it can be stored for up to 3 months.

FAQ

How can I make this dish dairy-free?

You can omit the cheese or use a dairy-free cheese alternative without losing the essence of the dish.

What is the prep time for the casserole?

The prep time is about 10 minutes, while the cook time takes around 20 minutes, making it quite a quick meal option.

Can I use frozen chicken?

While it’s best to use fresh chicken for this recipe, you can use thawed frozen chicken if that’s what you have on hand.

Conclusion

Incorporating flavorful dishes like this Keto Fajita Casserole into your meal rotation makes maintaining a low-carb lifestyle enjoyable. For more ideas, check out Keto Chicken Fajita Casserole – Low Carb and my Creamy Low Carb Chicken Casserole. Enjoy your cooking!

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