Chicken Fajita Casserole is a simple and tasty dish that brings all the best flavors of a fajita into one easy-to-make meal. It’s packed with tender chicken, colorful bell peppers, onions, and a lovely mix of spices that give it that classic fajita kick. The cheesy topping melts perfectly over everything, making it warm and comforting with every bite.
I love how this casserole saves time without losing any of the good stuff. Instead of standing by the stove juggling tortillas and fillings, everything cooks together in one dish. I usually make a big batch so we have leftovers for the next day—it warms up just as well and sometimes tastes even better after the flavors have mingled overnight.
The best way I like to serve it is with a dollop of sour cream and some fresh avocado or salsa on the side. It’s great for a casual weeknight dinner or even when friends come over and you want something tasty but not complicated. Chicken Fajita Casserole feels like a little fiesta in a dish, and it’s always a crowd-pleaser at my house!
Key Ingredients & Substitutions
Chicken: Cooked shredded chicken is key here. Rotisserie chicken works great to save time. If you want a leaner option, try skinless chicken thighs or even turkey.
Bell Peppers & Onion: Fresh, crisp peppers and onions add color and crunch. Use whatever colors you like—green, red, yellow—or even frozen sliced peppers if fresh aren’t available.
Cheese: I love the mix of cheddar and Monterey Jack for a gooey melt with a bit of sharpness. You can swap Monterey Jack for mozzarella or a Mexican cheese blend.
Fajita Seasoning: The seasoning mix brings the bold flavors to life. Homemade blends let you control salt and spice levels. Adjust chili powder or cumin to your preference.
Pasta (Optional): Adding pasta makes it heartier. Penne or rotini holds sauce well. For a low-carb twist, skip the pasta or swap with cooked rice or cauliflower rice.
How Do I Get Tender Peppers and Onions Without Losing Their Crunch?
Cooking the peppers and onions just right means softening them without turning mushy.
- Heat olive oil in a skillet over medium heat.
- Add sliced peppers and onions, stirring often.
- Cook for 5-7 minutes until they soften but still have a little bite.
- Avoid high heat to prevent burning or sogginess.
- This timing balances texture and flavor – soft is good, mushy is not.
I find stirring every minute helps them cook evenly and keep that bright color, which makes the casserole look and taste fresh.
Equipment You’ll Need
- Large skillet – I use it to cook the peppers, onions, and chicken, which makes mixing in the casserole easier later.
- Mixing bowl – helps combine the cooked ingredients and seasonings smoothly.
- 9×13 inch casserole dish – the perfect size for baking everything evenly and making serving easy.
- Measuring spoons and cups – ensures your seasonings and ingredients are just right.
- Oven – for baking the casserole until bubbly and golden on top.
Flavor Variations & Add-Ins
- Swap chicken for cooked shrimp or ground beef for different protein options that suit your taste.
- Use pepper jack or queso fresco instead of cheddar for extra cheesy flavor or spice.
- Add sliced jalapeños or hot sauce to kick up the heat.
- Mix in black beans, corn, or chopped tomatoes for more texture and flavor variety.
Chicken Fajita Casserole
Ingredients You’ll Need:
- 2 cups cooked chicken breast, shredded
- 1 red bell pepper, thinly sliced
- 1 yellow bell pepper, thinly sliced
- 1 medium onion, thinly sliced
- 2 cups cooked penne pasta or rotini (optional)
- 1 cup shredded cheddar cheese
- 1 cup shredded Monterey Jack cheese (or Mexican blend)
- 2 tbsp olive oil
- 1 packet fajita seasoning mix (or homemade mix: 1 tbsp chili powder, 1 tsp cumin, 1 tsp paprika, ½ tsp garlic powder, ½ tsp onion powder, salt and pepper to taste)
- ½ cup salsa (optional)
- Fresh cilantro, chopped (for garnish)
How Much Time Will You Need?
This recipe takes about 15 minutes to prep and cook the veggies and chicken mixture, plus 20-25 minutes to bake in the oven. The whole process is done in under 45 minutes, making it a quick and tasty dinner option.
Step-by-Step Instructions:
1. Cook the Veggies:
Preheat your oven to 375°F (190°C). Heat the olive oil in a large skillet on medium heat. Add the sliced red and yellow bell peppers and onion. Cook them, stirring often, for about 5-7 minutes until they are soft but still slightly crisp.
2. Add Chicken and Seasoning:
Add the shredded chicken to the skillet with the cooked vegetables. Sprinkle the fajita seasoning mix evenly over everything, and stir well to coat all the ingredients. If you’re using salsa, add it now and mix everything together.
3. Combine and Bake:
Put the chicken and veggie mixture into a large bowl. Add the cooked pasta if using and mix thoroughly. Transfer this mixture to a greased 9×13 inch casserole dish, spreading it out evenly. Sprinkle the shredded cheddar and Monterey Jack cheese over the top. Bake uncovered for 20-25 minutes or until the cheese melts, bubbles, and turns golden.
4. Serve:
Take the casserole out of the oven and let it cool for a few minutes. Garnish with fresh cilantro. Serve it with sour cream, guacamole, or extra salsa for a delicious fajita experience!
Can I Use Frozen Chicken for This Casserole?
Yes! Just make sure to thaw the chicken completely before shredding. You can thaw it overnight in the fridge or use the defrost setting on your microwave for quicker prep.
Can I Make This Casserole Ahead of Time?
Absolutely! Prepare the mixture and assemble the casserole, then cover and refrigerate for up to 24 hours before baking. Add a few extra minutes to the baking time if it’s chilled.
How Should I Store Leftovers?
Store leftovers in an airtight container in the fridge for up to 3 days. Reheat in the oven or microwave until heated through, stirring once for even warming.
What Can I Substitute for Pasta or Skip It?
If you want a lower-carb meal, simply omit the pasta. You can also swap with cooked rice, quinoa, or cauliflower rice for a different twist.