Preheat your oven to 350°F (175°C) and lightly grease a 9x13 inch baking dish.

Cook the pasta according to package instructions until al dente. Drain and set aside.

In a large skillet, melt the butter over medium heat. Add the minced garlic and red pepper flakes (if using) and sauté for about 1-2 minutes until fragrant, being careful not to burn the garlic.

Add the shrimp to the skillet, cooking for 2-3 minutes or until they are pink and fully cooked. Season with salt and pepper.

Pour in the heavy cream and half of the grated Parmesan cheese. Stir everything together and let it simmer for 2-3 minutes until slightly thickened.

In a large mixing bowl, combine the cooked pasta and shrimp mixture, ensuring everything is evenly mixed. Transfer the mixture to the prepared baking dish.

Top with the remaining Parmesan and all of the shredded mozzarella cheese.

Bake in the preheated oven for about 20-25 minutes or until bubbly and golden on top.

Remove from the oven, let rest for 5 minutes, and sprinkle with fresh parsley before serving.