Cheesy Chicken Fajita Casserole

The first time I made this casserole, I was trying to use up leftover rotisserie chicken and half a bag of peppers that were looking sad in the crisper drawer. My teenage son walked in from football practice and literally stopped in his tracks, asking what smelled so incredible. That night it became the most requested dinner in our house, and honestly, I make it even when I don't have leftovers because it's that good.

I served this at my sisters birthday dinner last fall, and her husband who claims to hate casseroles went back for thirds. The way the cheese gets all golden and bubbly on top while the peppers underneath turn sweet and tender is absolute magic.

Ingredients

• 3 cups cooked chicken breast: Rotisserie chicken works beautifully here and saves so much time
• 3 bell peppers, any colors: The mix of red, green, and yellow makes it gorgeous but use whatever you have
• 1 large onion, sliced: Sweet onions caramelize beautifully but yellow onions work perfectly fine
• 2 cups Mexican blend cheese: Pepper jack adds a nice kick if you want more heat
• 1/2 cup sour cream: Full fat tastes better but low fat works in a pinch
• 4 oz cream cheese, softened: Let it sit out while you prep everything else
• 10 oz diced tomatoes with green chilies: Rotel is the classic choice but any brand works
• 1 tsp chili powder: I use ancho chili powder for deeper flavor
• 1 tsp ground cumin: Toast it in a dry pan for 30 seconds to wake up the oils
• 1/2 tsp smoked paprika: This is what gives it that authentic fajita smokiness
• 1/2 tsp garlic powder: Fresh garlic burns too easily in this dish
• 1/2 tsp onion powder: Rounds out all the other flavors
• 1/4 tsp cayenne pepper: Skip if youre sensitive to heat
• 1 tbsp olive oil: For sautéing the vegetables
• Fresh cilantro and green onions: These bring a bright, fresh contrast to all that rich cheese

Instructions

Get your oven ready:

Preheat to 375°F and grab a 9x13 baking dish. I like to give it a quick spray with cooking oil even though the recipe is plenty rich already.

Sauté your vegetables:

Heat that olive oil in a big skillet over medium high heat. Toss in your sliced peppers and onions and let them cook for about 7 minutes until theyre soft and starting to get those lovely browned edges.

Mix everything together:

In a large bowl, combine your chicken, those gorgeous sautéed veggies, diced tomatoes with green chilies, and all your spices. Add the cream cheese and sour cream and mix until everythings coated and creamy. Season with salt and pepper.

Assemble and bake:

Spread the mixture into your prepared dish and cover it with all that shredded cheese. Bake for 25 to 30 minutes until the cheese is melted and bubbling and starting to turn golden in spots.

Rest and serve:

Let it sit for 5 minutes before serving. Sprinkle with fresh cilantro and green onions if you want something pretty and green on top.

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This recipe has gotten me through more weeknight dinner emergencies than I care to admit, and I love that it feels special enough for company but comes together in under an hour.

Make It Ahead

You can assemble this entire casserole up to 24 hours before baking. Just cover it tightly with foil and refrigerate, then add about 10 minutes to the baking time since it will be cold. The flavors actually develop more when they sit together.

Freezing Instructions

This freezes beautifully either before or after baking. I like to make two and freeze one unbaked for those nights when cooking feels impossible. Wrap it in plastic then foil and it will keep for 3 months.

Serving Suggestions

Warm flour tortillas on the side turn this into an interactive meal. Sometimes I serve it over cilantro lime rice for a heartier option.

• A simple green salad with lime dressing cuts through all that rich cheese
• Cornbread or tortilla chips add a nice crunch
• Sliced avocado on top is never a bad idea

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There is something so satisfying about a bubbling hot casserole coming out of the oven, and this one delivers every single time.

Recipe FAQs

→ Can I use rotisserie chicken for this casserole?

Yes, rotisserie chicken works perfectly and saves time. Simply shred about 3 cups and use it in place of cooked chicken breast.

→ How spicy is this casserole?

The base version has mild heat from the diced tomatoes with green chilies and spices. Adjust the spice level by adding more cayenne pepper or diced jalapeños.

→ Can I make this ahead of time?

Absolutely. Assemble the casserole, cover, and refrigerate for up to 24 hours before baking. Add 5-10 minutes to the baking time if baking cold.

→ What should I serve with this casserole?

Warm tortillas, Spanish rice, refried beans, or a fresh green salad complement this dish perfectly. It's hearty enough to stand alone too.

→ How do I store leftovers?

Store in an airtight container in the refrigerator for 3-4 days. Reheat in the microwave or oven at 350°F until heated through.

→ Can I freeze this casserole?

Yes, freeze before baking for up to 3 months. Thaw overnight in the refrigerator, then bake as directed. Already-baked portions can be frozen for 2-3 months.