Step 1: Bring a large pot of salted water to a boil. Add the penne pasta and cook until al dente, about 10 to 12 minutes, depending on your package. Drain and set aside.

Step 2: While the pasta cooks, season the chicken pieces with Italian seasoning, garlic powder, salt, and black pepper. Heat olive oil in a large deep skillet over medium-high heat. Add the chicken and cook for 6 to 8 minutes, turning occasionally, until golden brown and cooked through. Remove the chicken and set aside, keeping it warm.

Step 3: Reduce heat to medium in the same skillet. Melt the butter, then add minced garlic. Sauté for about 1 minute until fragrant, being careful not to burn the garlic.

Step 4: Whisk in the flour and cook for 1 minute, stirring constantly, to form a light roux.

Step 5: Slowly pour in the milk or half-and-half while whisking continuously to keep the sauce smooth. Let it simmer gently for 3 to 4 minutes until the sauce thickens.

Step 6: Stir in the grated Parmesan cheese and ¾ cup of the shredded mozzarella. Mix until the cheeses melt and the sauce is creamy and smooth. Add red pepper flakes if using. Taste and adjust seasoning with salt and pepper as needed.

Step 7: Add the cooked penne pasta and chicken to the skillet. Toss everything together gently until the pasta and chicken are evenly coated with the cheesy sauce.

Step 8: Sprinkle the remaining ¼ cup mozzarella over the top of the pasta. Cover the skillet and let it sit on low heat for 1 to 2 minutes to allow the cheese to melt into gooey ribbons.

Step 9: Garnish with freshly chopped parsley or basil. Serve immediately and enjoy every creamy, comforting bite.