Cheesy Chicken Fajita Casserole

The first time I made this casserole, I was trying to use up leftover chicken from a weekend roast and discovered something magical happens when fajita flavors get the oven treatment. My kitchen smelled absolutely incredible, the kind of aroma that makes neighbors pause when walking past your door.

I brought this to a potluck last winter, and three people immediately asked for the recipe. Thats when I knew this wasnt just a throw-together dinner, it was a keeper. Something about combining all those peppers and spices together creates layers of flavor you just cant get from skillet fajitas alone.

Ingredients

• 3 cups cooked chicken breast: Rotisserie chicken works beautifully here, just shred it into bite sized pieces
• 3 large bell peppers, one each red, green, and yellow: The mix of colors isnt just pretty, each brings a slightly different sweetness to the final dish
• 1 large onion, sliced: Sweet onions work best but yellow onions are perfectly fine too
• 2 cups shredded Mexican blend cheese: Dont skimp here, this cheese creates the topping everyone wants
• 1/2 cup sour cream plus 4 oz cream cheese: Together they make that creamy, tangy base that holds everything together
• 1 can (10 oz) diced tomatoes with green chilies: Drain these well or youll end up with a soupy casserole
• 1 tsp each chili powder, ground cumin, plus 1/2 tsp smoked paprika: This spice trio gives you that classic fajita profile without much effort
• 1/2 tsp each garlic powder and onion powder: Building flavor in the background
• 1/4 tsp cayenne pepper: Leave this out if youre feeding spice sensitive folks
• Salt and black pepper: Taste your mixture before adding, the canned tomatoes already contain salt
• 1 tbsp olive oil: For getting those peppers nice and soft
• Fresh cilantro and sliced green onions: The finishing touch that makes it look like you put in way more effort

Instructions

Preheat your oven to 375°F and grab a 9x13 baking dish:

A quick spray of cooking oil saves you serious scrubbing time later

Sauté the vegetables:

Heat that olive oil in your largest skillet over medium high heat, toss in all those sliced peppers and onions, cook for about 6 to 8 minutes until theyre soft and starting to caramelize

Mix everything together:

In a really large bowl, combine your chicken, those gorgeous sautéed vegetables, drained tomatoes, all the spices, both cheeses, and the sour cream, mix it until everything is well coated and evenly distributed

Assemble the casserole:

Spread the mixture into your prepared baking dish, then sprinkle the remaining shredded cheese all over the top in an even layer

Bake until golden and bubbly:

Pop it in the oven for 25 to 30 minutes, youre looking for hot bubbling edges and cheese thats turned golden brown in spots

Rest and garnish:

Let the casserole sit for about 5 minutes before serving, this helps it set up slightly, then scatter fresh cilantro and green onions on top

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My husband who normally claims he doesnt like casserooles went back for thirds the first time I made this. Now he specifically requests it when were having people over because it looks impressive but secretly comes together so quickly.

Make Ahead Magic

This casserole is one of those rare dishes that actually tastes better after sitting in the refrigerator for a day. The spices have time to really meld together and develop that slow cooked flavor without any actual slow cooking.

Serving Suggestions

I like to put out warm tortillas and let people make their own little fajita wraps right at the table. A simple green salad with lime vinaigrette cuts through all that rich cheese beautifully.

Customization Options

Substitute turkey or even a plant based chicken alternative, add black beans for extra protein, stir in some corn for sweetness, use pepper jack cheese if you want more heat, try different colored peppers based on what looks good at the market

• leftover steak makes an excellent substitute for chicken
• a sprinkle of lime juice right before serving brightens everything up
• avocado slices on top are never a bad idea

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This recipe has saved me on countless busy weeknights and fed many happy friends around my table. Hope it becomes a go to in your house too.

Recipe Questions

→ Can I use rotisserie chicken for this casserole?

Yes, a store-bought rotisserie chicken works perfectly and saves time. Simply shred or cube the meat and incorporate it into the mixture as directed.

→ How do I make this casserole spicier?

Add extra cayenne pepper to the seasoning blend or mix in diced jalapeños with the peppers. You can also use pepper jack cheese in place of part of the Mexican blend.

→ Can I assemble this casserole ahead of time?

Absolutely. Assemble the entire 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.

→ What can I serve with this fajita casserole?

Warm flour or corn tortillas, Spanish rice, refried beans, or a simple green salad all complement this dish beautifully. Guacamole and extra salsa make great toppings too.

→ Can I freeze this casserole?

Yes, you can freeze the unbaked casserole for up to 3 months. Thaw overnight in the refrigerator before baking as directed. Leftovers also freeze well in individual portions.

→ What type of cheese works best?

A Mexican blend that includes cheddar, Monterey Jack, and asadero works wonderfully. You can also use sharp cheddar alone or mix in some pepper jack for extra flavor.