Bring 2 cups of salted water to a boil in a medium saucepan.

Add the dry pasta and cook according to the package directions, about 8–10 minutes, until al dente. Drain and set aside.

While the pasta cooks, slice the chicken into thin strips and chop the onion and bell pepper.

Heat the olive oil in a large skillet over medium-high heat.

Add the onion and bell pepper and cook for 2 minutes until slightly softened.

Stir in the minced garlic and cook for about 30 seconds until fragrant.

Add the chicken strips, salt, pepper, and garlic powder. Cook for 5–6 minutes, stirring occasionally, until the chicken is browned and nearly cooked through.

Pour in the marinara sauce and stir well.

Cover the skillet and simmer for 5 minutes until the chicken is fully cooked.

Add the cooked pasta to the skillet and toss until evenly coated with the sauce.

Sprinkle in the mozzarella cheese and gently stir until melted.

If desired, transfer the skillet under the broiler for 2–3 minutes until the cheese becomes bubbly and lightly golden.

Garnish with Parmesan cheese and serve immediately.