Fajita Chicken Casserole

Prep Time: 20 minutes | Cook Time: 35–40 minutes | Total Time: 60 minutes
Yield: 8 servings | Intensity Level: Easy–Moderate

Introduction

Fajita Chicken Casserole takes everything you love about sizzling chicken fajitas — the smoky charred peppers, the tender seasoned chicken, the melty cheese, the warm tortillas — and bakes it all into one cozy, scoopable dish. It’s a weeknight hero: bold Tex-Mex flavor, a protein-packed filling, and only one baking dish to wash. The chicken is seasoned with a homemade fajita spice blend and seared for depth, then layered with sautéed bell peppers and onions, a creamy salsa-tinged sauce, and a generous blanket of Monterey Jack and cheddar. Torn tortillas form a soft, hearty base that soaks up all the juices, while the cheese melts into a golden, bubbly top. It’s endlessly adaptable — add black beans, corn, or jalapeños, or swap in rotisserie chicken to cut the prep time in half. Serve it with sour cream, avocado, and a squeeze of lime, and watch the whole family come back for seconds. It also freezes beautifully, making it a perfect batch-cook for busy weeks.

Ingredients

For the Fajita Seasoning

• 1 tbsp chili powder

• 1 tsp ground cumin

• 1 tsp smoked paprika

• 1 tsp garlic powder

• 1 tsp onion powder

• ½ tsp dried oregano

• ½ tsp kosher salt

• ¼ tsp cayenne pepper (optional, for heat)

For the Casserole

• 1½ lb (680 g) boneless, skinless chicken breasts, cut into 1-inch strips

• 2 tbsp olive oil, divided

• 1 large yellow onion, thinly sliced

• 1 large red bell pepper, thinly sliced

• 1 large green bell pepper, thinly sliced

• 1 large yellow or orange bell pepper, thinly sliced

• 3 cloves garlic, minced

• 1 can (10 oz / 285 g) diced tomatoes with green chiles (such as Rotel), drained

• 1 cup (240 ml) salsa (mild or medium)

• ½ cup (120 ml) sour cream

• 1 can (15 oz / 425 g) black beans, rinsed and drained (optional)

• 1 cup (150 g) frozen corn (optional)

• 8 small (6-inch) corn or flour tortillas, torn into bite-sized pieces

• 2 cups (230 g) shredded Monterey Jack cheese

• 1 cup (115 g) shredded sharp cheddar cheese

• 2 green onions, sliced (for garnish)

• 2 tbsp fresh cilantro, chopped (for garnish)

• Lime wedges, for serving

For Serving

• Sour cream or Greek yogurt

• Diced avocado or guacamole

• Salsa or pico de gallo

• Pickled jalapeños (optional)

Equipment

• Large skillet

• 9×13-inch baking dish

• Mixing bowls

• Whisk

• Chef’s knife and cutting board

• Aluminum foil

Time & Intensity Breakdown

Total active time: ~28 minutes | Total passive time: ~32 minutes

Instructions

Step 1: Make the Seasoning and Prep (8 minutes | Low Intensity)

In a small bowl, whisk together the chili powder, cumin, smoked paprika, garlic powder, onion powder, oregano, salt, and cayenne (if using). Pat the chicken strips dry and toss them with half the seasoning blend in a bowl. Slice the onion and bell peppers into thin, even strips. Mince the garlic. Preheat your oven to 375°F (190°C) and lightly grease a 9×13-inch baking dish.

Step 2: Sear the Chicken (6–7 minutes | Moderate–High Intensity)

Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the seasoned chicken in a single layer (work in two batches if needed — crowding steams the meat) and sear undisturbed for 3 minutes, then flip and cook 2–3 minutes more, until browned on the outside and just cooked through. The chicken will finish cooking in the oven, so slightly undercook it now to keep it tender. Transfer to a plate.

Step 3: Sauté the Peppers and Onions (6–8 minutes | Moderate Intensity)

Add the remaining 1 tablespoon of olive oil to the same skillet. Add the sliced onion and bell peppers and cook over medium-high heat for 6–7 minutes, stirring occasionally, until softened and lightly charred at the edges. Add the minced garlic and the remaining seasoning blend and cook 30 seconds, until fragrant. Remove from heat.

Step 4: Build the Sauce (3 minutes | Low Intensity)

In a medium bowl, stir together the drained diced tomatoes with green chiles, salsa, and sour cream until smooth. Taste and adjust the seasoning. If using black beans and corn, fold them into the pepper mixture now.

Step 5: Layer the Casserole (5 minutes | Low Intensity)

Spread half the torn tortillas in an even layer over the bottom of the prepared baking dish. Top with half the chicken and half the pepper mixture, then drizzle with half the sauce. Sprinkle with half the Monterey Jack and half the cheddar. Repeat the layers: remaining tortillas, chicken, peppers, sauce, and finally the remaining cheeses.

Step 6: Bake (25–30 minutes | Low Intensity, Passive)

Cover the dish loosely with foil and bake for 15 minutes. Remove the foil and bake another 10–15 minutes, until the cheese is melted, golden, and bubbling at the edges and the casserole is heated through. If the top is browning too quickly, tent loosely with foil again. Let it rest for 5 minutes before serving — this helps the layers set so it scoops cleanly.

Step 7: Garnish and Serve (2 minutes | Low Intensity)

Scatter the sliced green onions and chopped cilantro over the top. Serve hot with sour cream, avocado, salsa, pickled jalapeños, and lime wedges on the side.

Flavor Variations

• Green Chile Chicken: Swap the salsa for salsa verde and use pepper jack cheese.

• Loaded Fajita: Add black beans, corn, and a diced jalapeño for extra heartiness.

• Low-Carb: Replace the tortillas with cauliflower rice or omit them and bake the filling as a crustless casserole.

• Beef Version: Substitute thinly sliced flank steak or ground beef for the chicken.

• Spicier: Double the cayenne and add a diced serrano pepper with the bell peppers.

Serving Suggestions

Serve with a crisp green salad, Mexican rice, or warm tortillas on the side. It’s also great topped with a dollop of guacamole and a squeeze of fresh lime. For a party, set out bowls of toppings and let guests build their own plates.

Storage & Reheating

• Refrigerator: Store cooled leftovers in an airtight container for up to 4 days.

• Freezer: Freeze in portioned containers for up to 3 months. Thaw overnight in the fridge.

• Reheating: Warm in a 350°F (175°C) oven for 15–20 minutes, covered, until heated through. The microwave works for single portions but softens the tortillas.

Nutrition Information (Per Serving, Based on 8 Servings)

Values are estimates and will vary by cheese brand, tortilla type, and optional add-ins.