Step 1: Preheat Oven and Prepare Baking Dish: Preheat oven to 375F (190C). Lightly grease a 9x13 inch baking dish.
Step 2: Saut Chicken and Garlic: In a large skillet or Dutch oven, heat olive oil over medium heat. Add chicken pieces and cook until lightly browned on all sides. Add minced garlic and saut for about 1 minute, until fragrant. Do not fully cook the chicken at this stage.
Step 3: Create Alfredo Sauce: Sprinkle flour over the chicken and garlic mixture. Stir well to coat, cooking for another minute to remove the raw flour taste. Gradually whisk in low-fat milk, ensuring no lumps form. Bring to a simmer, stirring constantly.
Step 4: Add Pasta, Broccoli, and Cheese: Stir in the whole wheat penne pasta, broccoli florets, Italian seasoning, salt, and pepper. Bring the mixture back to a simmer, stirring occasionally to prevent sticking. Reduce heat to low, cover, and simmer for about 10 minutes, or until the pasta is partially cooked and has absorbed some of the sauce.
Step 5: Transfer to Baking Dish and Add Cheese: Pour the mixture into the prepared baking dish. Sprinkle cup of Parmesan cheese and Pecorino Romano cheese evenly over the top.
Step 6: Bake: Bake in the preheated oven for 25 minutes, or until the pasta is cooked through, the chicken is cooked completely, and the cheese is melted and lightly golden brown.
Step 7: Rest and Serve: Remove from the oven and let stand for 5 minutes before serving. Garnish with fresh parsley and red pepper flakes (if desired).
Optional Tips: For a creamier sauce, add 4 oz of cream cheese to the sauce while simmering. Substitute spinach for broccoli or add other vegetables like bell peppers. If you don't have Italian seasoning, use a mix of dried oregano, basil, rosemary, and thyme.