Heat oil in a large pot or deep skillet over medium-high heat. Season the chicken breasts with salt, pepper, Italian seasoning, and garlic powder on both sides. Once the oil is shimmering, add the chicken and sear for about 5 minutes until golden on the first side, then flip and cook another 3-4 minutes. Remove the chicken to a plate—it won't be fully cooked yet, but we're building flavor through browning. In the same pot, add the diced onion and minced garlic, stirring frequently for 2-3 minutes until fragrant and the onion begins to soften. Pour in the marinara sauce and water, scraping up any browned bits from the bottom of the pot. This deglazing step adds incredible depth to your sauce.

Bring the sauce to a gentle boil, then reduce heat to medium-low and add the seared chicken back into the pot along with the dried pasta. Stir well to distribute the pasta evenly and ensure it's submerged in the liquid as much as possible. I like to stir the pasta about halfway through cooking to prevent it from sticking together. Cover the pot and let everything cook for 10-15 minutes, stirring occasionally, until the pasta is tender and the chicken is cooked through (internal temperature should reach 165°F). The pasta will absorb flavor directly from the sauce while cooking, creating a more cohesive dish than cooking them separately.

Once the pasta is tender and chicken is fully cooked, remove the pot from heat and stir in the freshly grated Parmesan cheese and 1/4 cup of the mozzarella. The residual heat will melt these cheeses into the sauce, creating a creamy coating that binds everything together. The combination of Parmesan's sharp, nutty flavor with mozzarella's mild creaminess creates the classic richness of chicken parm pasta.

Transfer the entire mixture to a 9x13 inch baking dish or similar size. Spread the remaining 3/4 cup of shredded mozzarella evenly over the top. Place under a preheated broiler for 2-3 minutes, watching carefully to prevent burning, until the cheese is melted and lightly golden. This final step gives you that restaurant-style bubbly, slightly browned cheese top that makes the dish feel special.

Remove from the broiler and let rest for 1-2 minutes. Sprinkle the torn fresh basil, chopped fresh parsley, and additional dried Italian seasoning over the top just before serving. The fresh herbs add brightness and color to contrast the rich, cheesy dish.