Cook the penne pasta according to the package instructions, reserving at least 1/2 cup of the cooking liquid.

In a large skillet over medium-high heat, heat 1 1/2 teaspoons of the olive oil and add the sliced onion and bell peppers.

Sprinkle with 1 tablespoon of fajita seasoning and cook for about 5-6 minutes until slightly charred and tender.

Transfer the vegetables to a bowl and set aside.

Add the remaining 1 1/2 teaspoons of olive oil to the skillet and season the chicken cubes with 2 tablespoons of fajita seasoning.

Cook for 5-6 minutes, stirring occasionally, until the chicken is cooked through and no longer pink.

Return the sautéed onion and peppers to the skillet, add the cooked pasta, 1 1/2 cups of shredded cheese, and the remaining tablespoon of fajita seasoning.

Pour in 1/4 cup of the reserved pasta cooking liquid and stir until well combined and the cheese has melted.

Serve with a sprinkle of remaining cheese and desired toppings like diced avocado or guacamole.