Fajita Chicken Casserole brings all the sizzle of classic Tex-Mex fajitas into one easy, crowd-pleasing bake. This one-dish wonder layers tender chicken, vibrant peppers and onions, creamy sauce, and melted cheese for a meal that’s as simple to assemble as it is delicious to devour. Below, you’ll find step-by-step instructions, inspiring variations, and expert tips to ensure your casserole comes out perfectly every time.

Table of Contents

Why You’ll Love This Fajita Chicken Casserole

One-Dish Dinner: No skillet and side dishes—everything bakes together in one pan.
Customizable: Swap proteins, adjust spice levels, or mix in extra veggies.
Family-Friendly: Loved by kids and adults alike, with leftovers that reheat beautifully.
Quick Cleanup: Fewer dishes means more time to relax after dinner.

Origins & Inspiration

Classic fajitas originated in Tex-Mex kitchens, where marinated strips of skirt steak or chicken were grilled alongside onions and bell peppers. Translating that vibrant flavor into a casserole makes for an easy weeknight solution—no grill required. In this version, everything is layered and baked, concentrating the savory juices and melding the seasonings into every bite.

Early Tex-Mex cooks realized that piling ingredients together in a pan not only simplified prep but also let them stretch modest ingredients into a hearty family meal. Today’s spin combines the comfort of a baked casserole with the bold, colorful flavors of fajitas. Plus, by baking until bubbly, you get beautifully browned cheese and tender chicken that meets the USDA’s recommended Chicken safe cooking temperature of 165 °F (74 °C).

Ingredients & Substitutions

Use fresh, seasonal produce when possible, but feel free to adapt based on what you have on hand.

Chicken
- 2 lbs boneless, skinless chicken breasts or thighs, cut into 1″ pieces
- Rotisserie chicken is a great shortcut—simply shred and stir in at the end
Vegetables
- 3 bell peppers (red, yellow, green), thinly sliced
- 1 large yellow onion, thinly sliced
- Optional: 1 cup frozen corn or diced tomatoes
Cheese
- 2 cups shredded cheddar, pepper jack, or a Mexican blend
Base Options
- 2 cups cooked white or brown rice
- 6 small corn or flour tortillas, torn into bite-sized pieces
- Low-carb: 2 cups riced cauliflower
Sauce
- 1 cup sour cream or Greek yogurt
- 1 can (10½ oz) cream of chicken soup (or homemade white sauce)
- 1 cup salsa (store-bought or fresh)
Seasoning
- 2 Tbsp store-bought fajita mix or 3 Tbsp homemade fajita seasoning mix (see below)
Optional Add-Ins
- 1 can black beans, drained
- 1 cup fresh spinach or kale
- Sliced jalapeños for extra heat

Equipment & Tools

9×13″ baking dish or large oven-safe skillet
Chef’s knife and cutting board
Mixing bowls and measuring cups/spoons
Spatula or large spoon
Aluminum foil or casserole lid

Step-by-Step Preparation

Preheat & Prep
- Preheat the oven to 400 °F (200 °C).
- Lightly grease the baking dish or skillet.
Season & Cook Chicken
- In a bowl, toss the chicken pieces with 1 Tbsp oil and the fajita seasoning.
- In a hot skillet over medium-high heat, cook chicken until lightly browned but not fully cooked, about 4 minutes per side. Set aside.
Sauté Vegetables
- In the same skillet, add a drizzle of oil and sauté peppers and onions until just tender, about 5 minutes.
Combine Base & Sauce
- In a large bowl, stir together rice (or tortillas), sour cream, cream soup, salsa, and 1 Tbsp seasoning.
Assemble Layers
- Spread half of the base mixture across the dish.
- Top with half the chicken and veggies.
- Sprinkle with 1 cup cheese.
- Repeat layers, finishing with cheese on top.
Bake
- Cover with foil and bake 20 minutes.
- Remove foil and bake another 10 minutes until cheese is bubbly and golden.
Rest & Garnish
- Let stand 5 minutes to set.
- Top with fresh cilantro, lime wedges, sliced avocado, or pico de gallo.

Cheesy baked fajita chicken casserole garnished with cilantro and limefajita-chicken-casserole

Homemade Fajita Seasoning Mix

Mix and store in an airtight jar for up to six months.

Ingredients
- 2 Tbsp chili powder
- 1 Tbsp ground cumin
- 1 Tbsp paprika
- 1 tsp garlic powder
- 1 tsp onion powder
- 1 tsp dried oregano
- ½ tsp salt
- ½ tsp black pepper
- Optional heat: ¼ tsp cayenne or chipotle powder
Method
1. Combine all spices in a small bowl.
2. Whisk to blend thoroughly.
3. Store in a sealed jar, shaking before each use.

Variations & Add-Ins

Low-Carb/Keto: Replace rice with cauliflower rice, use full-fat cheese, omit tortillas.
Vegetarian: Swap chicken for black beans or cubed tofu; add extra veggies.
Spicy Heat: Stir in pickled jalapeños, use habanero powder, or drizzle hot sauce.
Family-Style: Double the recipe to feed a crowd; bake in two 9×13″ dishes.
Tex-Mex Fusion: Top with guacamole, drizzle Mexican crema, or serve with warmed tortillas.

Make-Ahead & Meal-Prep Tips

Assemble Ahead: Prepare up to 24 hours in advance; cover and refrigerate.
Freezing: Assemble uncooked casserole, wrap tightly, and freeze up to 3 months.
Thawing: Thaw overnight in refrigerator before baking.
Reheating: From fridge, bake at 350 °F (175 °C) for 15 minutes; from frozen, add 10 minutes.

Storage & Reheating

Refrigerator: Store leftovers in airtight containers for up to 4 days.
Freezer: Freeze portions in freezer-safe containers for up to 3 months.
Reheat:
- Oven: 350 °F until warm (10–15 minutes).
- Microwave: 2–3 minutes on high, stirring halfway.

Serving Suggestions & Pairings

Sides
- Mexican rice or cilantro lime rice
- Black beans or refried beans
- Tortilla chips with salsa or queso
Toppings
- Sour cream or Greek yogurt
- Fresh pico de gallo, guacamole, or sliced avocado
- Chopped cilantro, lime wedges, pickled onions
Beverages
- Classic margaritas or palomas
- Agua fresca (horchata, tamarind, or jamaica)
- Iced tea or Mexican Coke

Troubleshooting & Expert Tips

Soggy Casserole:
- Drain excess liquid from sautéed veggies.
- Use less creamy sauce or cook longer uncovered.
Dry Chicken:
- Don’t overcook before baking; finish cooking in oven.
- Marinate chicken 15 minutes beforehand for extra moisture.
Uneven Layers:
- Stir base mixture thoroughly to distribute sauce.
- Let casserole rest before slicing to set layers.
Flavor Boost:
- Add a splash of lime juice before serving.
- Sprinkle smoked paprika for depth.

FAQs

Can I use rotisserie chicken?
Yes—toss shredded rotisserie chicken with seasoning and layer directly. Saves roughly 15 minutes.
How do I make it gluten-free?
Use corn tortillas, check that cream soup is labeled gluten-free, or substitute homemade white sauce.
What’s the best reheating method?
For crisp cheese, reheat in a 350 °F oven until warmed through. Microwave works for quick single servings.
Can I replace rice with cauliflower rice?
Absolutely—treat it the same way, though cauliflower rice releases more moisture, so reduce sauce slightly.
How long can I freeze the casserole?
Up to 3 months in a well-sealed freezer container. Thaw overnight before baking.
How do I adjust the spice level?
Increase or decrease cayenne in the seasoning mix, or top with hot sauce and jalapeños to taste.
Is there a slow-cooker version?
Yes—layer ingredients in a 6-quart slow cooker, cook on Low for 4–5 hours or High for 2–3. Add cheese in the last 30 minutes.

Conclusion

With its bold Tex-Mex flavors, easy preparation, and endless customization options, Fajita Chicken Casserole is the perfect solution for busy evenings, potlucks, or casual family dinners. Whether you stick to the classic build or experiment with low-carb, vegetarian, or extra-spicy variations, this one-dish bake is sure to become a regular in your meal rotation. Gather your ingredients, fire up the oven, and get ready to enjoy the ultimate fusion of convenience and flavor!