• Step 1: Preheat your oven to 375°F (190°C). Cook the pasta shells according to the package instructions until al dente. Drain and set aside to cool slightly.
• Step 2: In a large mixing bowl, combine the cooked and shredded chicken, steamed and chopped broccoli, ricotta cheese, 1/2 cup of the mozzarella cheese, and the Parmesan cheese. Mix well and season with salt and pepper to taste.
• Step 3: In a saucepan, melt the butter over medium heat. Add the minced garlic and cook for 1 minute, until fragrant. Whisk in the flour and cook for 2 minutes, stirring constantly. Gradually pour in the milk, whisking continuously to prevent lumps from forming. Bring the mixture to a simmer and cook for 5-7 minutes, or until the sauce has thickened. Remove from heat and stir in the heavy cream.
• Step 4: Spoon the chicken and broccoli filling into the cooked pasta shells, arranging them in a baking dish. Pour the Alfredo sauce over the filled shells, making sure to coat them evenly.
• Step 5: Sprinkle the remaining 1/2 cup of mozzarella cheese over the top of the shells. Bake for 20-25 minutes, or until the cheese is melted and bubbly.
• Step 6: Remove the dish from the oven and let it cool for 5 minutes before serving. Garnish with chopped parsley or basil, if desired.