Step 1: Preheat and Prepare
Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish with non-stick cooking spray or a light brush of olive oil to prevent sticking.

Step 2: Cook the Tortellini
Bring a large pot of salted water to a boil. Add the tortellini and cook according to the package instructions, usually about 3-5 minutes for refrigerated tortellini. Be careful not to overcook; the pasta should be al dente. Drain and set aside.

Step 3: Make the Alfredo Sauce
In a large saucepan over medium heat, melt the butter. Add the minced garlic and sauté for about 1-2 minutes until fragrant but not browned. Pour in the heavy cream and bring to a gentle simmer. Reduce the heat to low and whisk in the Parmesan cheese until the sauce is smooth and thickened, about 3-5 minutes. Season with salt, black pepper, and a pinch of nutmeg if desired. Remove from heat.

Step 4: Combine Tortellini and Sauce
Gently fold the cooked tortellini into the Alfredo sauce until well coated. If you’re adding cooked chicken, mushrooms, or broccoli, mix them in at this stage.

Step 5: Assemble in Baking Dish
Pour the tortellini mixture into the prepared baking dish, spreading it evenly. Sprinkle the shredded mozzarella over the top, followed by the grated Parmesan.

Step 6: Bake
Place the baking dish in the preheated oven and bake for 20-25 minutes, or until the cheese is bubbly and golden brown. If the cheese is browning too quickly, you can cover the dish loosely with aluminum foil.

Step 7: Garnish and Serve
Remove from the oven and let the dish cool for a few minutes. Sprinkle chopped fresh parsley over the top before serving.