Cheesy Chicken Fajita Casserole

The first time I made this casserole, my husband took one bite and declared it better than our favorite fajita spot. I stumbled on the combination when I had leftover rotisserie chicken and a craving for something cheesy and comforting.

Last winter, I brought this to a friend's potluck dinner, and honestly, it was gone before I could even grab a plate. People kept asking what was in it, but the real secret is just letting those peppers get nicely caramelized before they hit the casserole dish.

Ingredients

• 3 cups cooked chicken breast: Rotisserie chicken works beautifully here, just shred it with your hands for the best texture
• 3 bell peppers, mixed colors: The red ones add sweetness while green brings a slight bitterness that balances the rich cheese
• 1 large onion, sliced: White onions caramelize better than sweet onions for this dish
• 2 cups Mexican blend cheese: I grate my own from blocks because pre-shredded cheese has anti-caking agents that prevent proper melting
• 1/2 cup sour cream and 4 oz cream cheese: This duo creates that silky, tangy base that ties everything together
• 10 oz can diced tomatoes with green chilies: Drain them really well or your casserole will be too soupy
• Chili powder, cumin, smoked paprika: These three spices are the holy trinity of fajita flavor, so do not skip the smoked paprika
• Garlic powder, onion powder, cayenne: The cayenne is optional but I always add a pinch because that gentle heat wakes up all the other flavors
• Fresh cilantro and green onions: Add these right before serving because they lose their bright punch in the oven

Instructions

Get your oven ready:

Preheat to 375°F and grease a 9x13 dish with butter or cooking spray, really getting into the corners

Sauté your vegetables:

Heat olive oil in a large skillet over medium-high heat and cook the peppers and onions for 6 to 8 minutes until they are soft and starting to turn golden

Mix everything together:

Combine the chicken, sautéed vegetables, drained tomatoes, all the spices, cream cheese, and sour cream in a large bowl, then season generously with salt and pepper

Assemble the casserole:

Spread the mixture evenly in your prepared dish and cover the top completely with shredded cheese

Bake until bubbly:

Cook uncovered for 25 to 30 minutes until the cheese is melted and starting to turn golden brown in spots

Let it rest and garnish:

Wait 5 minutes before serving, then sprinkle with fresh cilantro and green onions if you want that pop of color

Save

My kids now request this for their birthday dinner instead of pizza, which says everything about how good it is. It has become our go-to when we want something that feels special but does not require hours of work.

Make It Your Own

Try swapping the chicken for leftover turkey after Thanksgiving or use shrimp if you want something lighter. The base recipe is so forgiving that you can play around with different proteins without worrying about ruining the dish.

Serving Ideas

I love setting up a toppings bar with extra sour cream, sliced avocado, and hot sauce so everyone can customize their portion. Warm flour tortillas on the side turn this into an interactive meal that feels like a fiesta.

Storage And Prep

This casserole actually tastes better the next day when all the flavors have had time to meld together. I often assemble it the night before and keep it in the refrigerator, then just pop it in the oven when I get home from work.

• You can freeze this unbaked for up to 3 months, just thaw overnight before baking
• Add an extra 10 minutes to the baking time if it goes into the oven cold from the fridge
• The leftovers reheat beautifully in the microwave for a quick lunch

Save

There is something so satisfying about a casserole that delivers all the flavors you love without any of the fuss. This is the kind of recipe that makes weeknight dinners feel like a special occasion.

Recipe FAQs

→ Can I use rotisserie chicken?

Yes, rotisserie chicken works perfectly and saves time. Simply shred about 3 cups from a store-bought rotisserie chicken and add it directly to the mixture. The seasoned meat adds extra flavor to the casserole.

→ Can I make this ahead of time?

Absolutely. Assemble the complete casserole, cover tightly, and refrigerate for up to 24 hours before baking. You may need to add 5-10 minutes to the baking time if baking cold from the refrigerator.

→ How can I make it spicier?

Increase the cayenne pepper to 1/2 teaspoon, add diced jalapeños with the bell peppers, or use pepper jack cheese in place of half the Mexican blend. You can also add a few dashes of hot sauce to the creamy mixture.

→ What should I serve with this casserole?

Warm flour or corn tortillas, Mexican rice, refried beans, or a crisp green salad make excellent sides. Fresh guacamame, pico de gallo, or extra sour cream also complement the rich, cheesy flavors.

→ Can I freeze this casserole?

Yes, freeze before baking. Assemble in a freezer-safe dish, wrap tightly, and freeze for up to 3 months. Thaw overnight in the refrigerator before baking as directed, adding extra time if needed.

→ What cheese works best?

Mexican blend cheese is ideal because it melts beautifully and includes mild cheddar, Monterey Jack, and asadero. For extra flavor, try adding some sharp cheddar or pepper jack to the mix.