Keto Spicy Fajita Chicken Casserole: The Only Recipe You’ll Want for Dinner

If you’re stuck figuring out what’s for dinner, and you’re trying to keep things low-carb but still crave something filling and packed with flavor, this Keto Spicy Fajita Chicken Casserole might just save the day. It’s one of those throw-everything-in-the-pan kind of meals, but with flavors so bold you’d swear you spent hours in the kitchen.

You won’t need a pantry full of odd ingredients or any chef skills here. Just a few simple items, a bit of chopping, and about 35 minutes of oven time. Easy enough to throw together after work, and tasty enough to make you forget about missing tortillas or rice.

So, let’s get straight into it, because no one has time to scroll through long backstories when their stomach’s growling.

What Makes This Keto Fajita Chicken Casserole So Good?

Here’s the thing. Most casseroles tend to lean on pasta, potatoes, or rice to fill them out. That’s fine if carbs are your friend. But if you’re running the keto route, those extras are off the table. What makes THIS casserole work is swapping out all the filler carbs and replacing them with juicy, seasoned chicken, crunchy bell peppers, onions, and melty cheese, all the parts of fajitas you actually care about, just layered up into one cozy dish.

It’s spicy, creamy, cheesy, with a slight smoky kick, and won’t boot you out of ketosis. Plus, fewer dishes. Win-win.

Ingredients You’ll Need:

Everything on this list is easy to find at any grocery store. No fancy keto ingredients. No weird flours or powders. Just stuff you probably already have or can grab quickly.

For the casserole:

• 1.5 lbs boneless skinless chicken breasts (or thighs, if you like it juicier)
• 1 tablespoon olive oil
• 1 red bell pepper, sliced
• 1 yellow bell pepper, sliced
• 1 green bell pepper, sliced
• 1 medium red onion, sliced
• 2 teaspoons chili powder
• 1 teaspoon smoked paprika
• 1 teaspoon garlic powder
• 1 teaspoon cumin
• 1/2 teaspoon onion powder
• 1/2 teaspoon salt
• 1/2 teaspoon black pepper
• 1/4 teaspoon cayenne pepper (optional but gives it a good kick)
• 1 cup shredded cheddar cheese
• 1 cup shredded Monterey Jack cheese
• 1/2 cup sour cream
• 4 oz cream cheese, softened
• 1/4 cup heavy cream
• Juice of 1 lime
• Fresh cilantro for garnish (optional, but totally worth it)

Quick Ingredient Swap Ideas:

• Not a fan of chicken breast? Use chicken thighs. They’re fattier, more flavorful, and stay super juicy.
• Want more veggies? Mushrooms, zucchini, or spinach work well. Just sauté them first to cook off extra moisture.
• Need dairy-free? Use dairy-free cheese and coconut cream instead of heavy cream. It won’t melt exactly the same, but still delicious.

Let’s Get Cooking:

1. Preheat & Prep

Heat your oven to 375°F (190°C).

While that’s heating, grab a large skillet or frying pan. Heat the olive oil over medium-high heat.

2. Season the Chicken

Slice your chicken breasts into thin strips (think fajita-style). Toss them in a bowl with chili powder, paprika, cumin, garlic powder, onion powder, salt, pepper, and cayenne. Coat evenly.

3. Sear the Chicken

Add the chicken strips to the hot skillet. Cook for about 4-5 minutes until they start browning but don’t worry about cooking them fully, they’ll finish in the oven. Pull them out and set aside.

4. Cook the Veggies

In the same pan, toss in the sliced peppers and onions. You want them soft but still holding some bite, around 5 minutes. Sprinkle a little salt while they’re cooking to help them release moisture.

5. Make It Creamy

In a separate bowl, mix the cream cheese, sour cream, and heavy cream together. It might look a bit lumpy at first but keep stirring, it’ll smooth out. Squeeze in the lime juice. Taste it. Add a pinch of salt if you feel like it.

6. Assemble

Get your casserole dish (9×13 inch works well). Layer in:

• First, spread the cooked chicken.
• Add the sautéed peppers and onions over the top.
• Spoon the cream cheese mixture over everything, spreading it gently so it covers.
• Sprinkle both cheeses evenly on top.

7. Bake

Pop it in the oven, uncovered, for about 25 minutes. You’ll know it’s ready when the cheese is bubbly and starting to brown a bit on top.

8. Garnish & Serve

Sprinkle fresh cilantro over the top. Maybe even slice up a few extra limes on the side. Serve hot!

How to Store & Reheat

Leftovers? You’re lucky if there are any, honestly. But if there are:

• Fridge: Store in an airtight container. Keeps for 3-4 days.
• Freezer: Wrap portions tightly in plastic wrap, then foil. Good for up to 2 months. Thaw overnight in the fridge before reheating.
• Reheating: Microwave works, but if you’ve got time, reheat in the oven at 350°F until hot. Keeps the cheese nice and melty.

Add-Ons & Custom Tweaks

You don’t have to stop at the basic recipe. Here’s how you can spin it:

• Add sliced jalapeños right before baking if you’re feeling extra spicy.
• Top with diced avocado or guacamole after baking. Adds creaminess without extra carbs.
• Crushed pork rinds sprinkled on top can give a crunchy crust without breading.
• Serve over cauliflower rice if you want more bulk but still keto.

Why This Casserole Recipe Works for Keto

A lot of people mess up keto casseroles by overloading them with “substitute” ingredients trying to recreate pasta or bread. Here, we skip the fuss. It’s all whole ingredients, chicken, peppers, cheese, cream. All low-carb, high-fat, and filling.

Each serving comes in around 5-6g net carbs depending on portion size and exact veggies used. So it’s well within your carb count for the day while keeping you full and satisfied.

Personal Touch: The First Time I Made This…

Quick story. First time I tried to make a keto casserole, it was honestly a disaster. I threw in too much cauliflower, overloaded it with weird low-carb thickeners, and the whole thing turned into soggy mush. Lesson learned, keep it simple.

I switched gears, thought about what I actually like about fajitas: the juicy chicken, smoky spices, melty cheese. Left out the extras, focused on those core flavors, and bam, the casserole became a go-to in our house.

Even the non-keto folks at my table ask for seconds.

Final Pro Tips:

• Don’t skip the lime juice. It brightens the dish and cuts through the richness.
• Slice your chicken evenly. Keeps cooking time predictable and ensures everything is done at the same time.
• Let it rest a few minutes after baking. Cheese settles, flavors meld, totally worth waiting.

Mark This Recipe, Save It, Make It Weekly

This isn’t one of those recipes you make once and forget. It’s a crowd-pleaser, meal-prep friendly, and doesn’t require you to stand over the stove for hours. Plus, the ingredients are flexible enough that you can tweak based on whatever’s left in your fridge.

Got picky eaters? Dial down the spice.

Short on time? Pre-cook the chicken and veggies earlier in the day.

Eating solo? Make it once, and you’ve got lunch for the next few days.

It’s one of those casseroles that earns a permanent spot in the meal rotation, whether you’re doing keto for life, or just want to eat something hearty without the carb crash.

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