Fajita chicken casserole

This fajita chicken casserole is a delicious, comforting dish that's full of bold flavors and colors. It blends tender chicken pieces with vibrant bell peppers, onions, and classic fajita seasoning,…

By Willow • November 25, 2025 • Reading time: 6 min

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This fajita chicken casserole is a delicious, comforting dish that’s full of bold flavors and colors. It blends tender chicken pieces with vibrant bell peppers, onions, and classic fajita seasoning, all baked together with melted cheese and a touch of creamy goodness. The result is a warm, easy meal that feels like a fiesta in every bite.

I love making this casserole when I want something that’s both quick to throw together and packed with flavor. One of my favorite parts is how the fajita seasoning spices up the chicken and veggies without being too overpowering. Plus, the melted cheese on top brings everything together perfectly. A little tip: use a mix of green, red, and yellow peppers for the best look and taste.

Serving this fajita chicken casserole with a side of rice or wrapped up in warm tortillas makes it a complete meal that everyone enjoys. It’s also great when you have friends or family over, because it’s easy to share and hard to resist going back for seconds. Whenever I make it, I feel like I’m sharing a simple, tasty meal that brings people together around the table.

Key Ingredients & Substitutions

Chicken: Boneless, skinless chicken breasts work well here because they cook quickly and stay tender. You can swap with chicken thighs if you want juicier meat; they also hold up nicely in the casserole.

Bell Peppers & Onions: The mix of red and green peppers adds color and crunch. If you prefer milder flavors, use just one type of pepper or add some yellow for sweetness. Onions bring a subtle sweetness when sautéed.

Fajita Seasoning: The blend of chili powder, cumin, and smoked paprika is key to that fajita flavor. If you don’t have smoked paprika, regular paprika is fine. Adjust cayenne to control heat or skip if you want it mild.

Cheese: Cheddar and Monterey Jack melt beautifully and give a creamy, cheesy top. You could use pepper jack for more spice or mozzarella for a milder taste.

Sour Cream or Mexican Crema: This adds creaminess and slight tang. Greek yogurt is a good substitute if you want a lighter option.

How Do I Get Perfectly Cooked Chicken and Veggies Without Overcooking?

Cooking the chicken and vegetables just right is important to keep them tender and flavorful in the casserole. Follow these steps for best results:

• Chicken: Cook the seasoned chicken strips on medium-high heat until browned and cooked through, about 5-7 minutes. Don’t overcook, as they will cook more in the oven.
• Vegetables: Sauté the sliced onions and peppers for about 5 minutes until softened but still crisp. This keeps them from getting mushy after baking.
• Layering: Mix the chicken and veggies with salsa and sour cream to keep the casserole moist and creamy.
• Baking: Bake just until the cheese melts and bubbles, about 15-20 minutes. This gentle baking finishes cooking everything together without drying out the dish.

Equipment You’ll Need

• 9×13 inch casserole dish – perfect size for mixing and baking everything evenly.
• Large skillet – great for cooking chicken and sautéing peppers and onions in one pan.
• Mixing bowl – to toss chicken with spices and blend the filling ingredients smoothly.
• Sharp knife – makes slicing chicken and vegetables quick and safe.
• Measuring spoons – to get the spice amounts just right for balanced flavor.

Flavor Variations & Add-Ins

• Swap chicken for sliced steak or shrimp for a different protein twist that still tastes great with fajita spices.
• Use pepper jack cheese instead of Monterey Jack for a spicier cheesy top.
• Add black beans or corn to increase fiber and make it more filling.
• Mix in diced tomatoes or a splash of lime juice before baking for a fresh burst of flavor.

Fajita Chicken Casserole

Ingredients You’ll Need:

For The Chicken and Veggies:

• 1.5 lbs boneless, skinless chicken breasts, cut into strips
• 1 large red bell pepper, sliced
• 1 large green bell pepper, sliced
• 1 medium onion, sliced
• 2 tablespoons olive oil

For The Seasoning:

• 2 teaspoons chili powder
• 1 teaspoon ground cumin
• 1 teaspoon smoked paprika
• ½ teaspoon garlic powder
• ½ teaspoon onion powder
• ¼ teaspoon cayenne pepper (optional, for heat)
• Salt and freshly ground black pepper, to taste

For The Casserole:

• 1 cup salsa (mild or spicy, based on preference)
• 1 cup shredded cheddar cheese
• 1 cup shredded Monterey Jack cheese
• ½ cup sour cream or Mexican crema
• 1-2 fresh jalapeños, sliced (for garnish)
• Fresh cilantro, chopped (optional for garnish)

How Much Time Will You Need?

You’ll spend about 15 minutes preparing and cooking the chicken and veggies on the stove. Then, the casserole bakes in the oven for 15-20 minutes until the cheese is perfectly melted and bubbly. All together, about 35 minutes from start to finish.

Step-by-Step Instructions:

1. Get Ready:

Preheat your oven to 375°F (190°C). Lightly grease a 9×13 inch casserole dish so nothing sticks.

2. Season the Chicken:

In a large bowl, mix together chili powder, cumin, smoked paprika, garlic powder, onion powder, cayenne (if using), salt, and pepper. Add chicken strips and toss to coat well with the spices.

3. Cook Chicken and Veggies:

Heat olive oil in a large skillet over medium-high heat. Add the chicken and cook it until browned and cooked through, about 5-7 minutes. Remove the chicken and set aside. In the same skillet, add the sliced onions and peppers and sauté for about 5 minutes until they are soft but still have a little crispness.

4. Mix the Filling:

In a large bowl, combine the cooked chicken, sautéed veggies, salsa, and sour cream. Stir everything together to blend the flavors.

5. Assemble and Bake:

Spread the mixture evenly into your prepared casserole dish. Sprinkle the shredded cheddar and Monterey Jack cheeses evenly on top. Bake in the oven for 15-20 minutes until the cheese is melted and bubbly.

6. Finish and Serve:

Take the casserole out of the oven and let it sit a few minutes to cool slightly. Garnish with sliced jalapeños and fresh cilantro if you like some extra spice and freshness. Serve warm on its own, or with rice or tortillas.

Can I Use Frozen Chicken for This Casserole?

Yes, you can! Just make sure to fully thaw the chicken in the fridge overnight before cooking. Pat it dry to remove excess moisture so it sautés nicely.

How Do I Store Leftovers?

Store any leftovers in an airtight container in the refrigerator for up to 3 days. Reheat gently in the oven or microwave until warmed through.

Can I Make This Recipe Ahead of Time?

Absolutely! Prepare the filling and assemble the casserole, then cover and refrigerate for up to 24 hours before baking. Just add a few extra minutes to the baking time if baking from cold.

What Can I Substitute for Bell Peppers?

If you’re not a fan of bell peppers, try using zucchini or mushrooms instead. They’ll still add great texture and soak up the fajita flavors nicely.