Creating the Creamy Garlic Shrimp Pasta Bake is straightforward when you follow these easy steps:

1. Preheat Oven: Begin by preheating your oven to 350°F (175°C).
2. Cook Pasta: In a large pot of salted boiling water, cook the penne pasta according to package instructions until al dente. Drain and set aside.
3. Sauté Shrimp: In a skillet, melt the butter over medium heat. Add the minced garlic and sauté for about 1 minute until fragrant.
4. Add Shrimp: Place the shrimp in the skillet and cook until they turn pink, around 3-4 minutes. Season with salt, pepper, and red pepper flakes, if using.
5. Prepare Sauce: Pour in the heavy cream and bring to a gentle simmer. Stir in half of the Parmesan cheese, mixing until melted and creamy.
6. Combine Ingredients: In a large mixing bowl, combine the cooked pasta, shrimp, sauce, and chopped spinach. Mix until everything is evenly coated.
7. Transfer to Baking Dish: Pour the pasta mixture into a greased 9×13-inch baking dish.
8. Top with Cheese: Sprinkle the remaining Parmesan cheese evenly over the top.
9. Bake: Place the dish in the oven and bake for about 15-20 minutes, or until the top is golden and bubbly.
10. Garnish: Remove from the oven, let cool for a few minutes, and garnish with fresh parsley.

These steps will help you create an incredible Creamy Garlic Shrimp Pasta Bake that is sure to be a hit!