Creating Pasta alla Sorrentina is easier than you might think. Just follow these simple steps:

1. Cook the Pasta: Boil a large pot of salted water. Add the pasta and cook according to package instructions until al dente. Reserve a cup of pasta water before draining.
2. Sauté the Onion and Garlic: In a large pan, heat the olive oil over medium heat. Add the chopped onion and cook until soft and translucent, about 5 minutes. Stir in the minced garlic and sauté for another minute until fragrant.
3. Add the Tomatoes: Pour in the canned crushed tomatoes, stirring well. Season with salt, pepper, and optional red pepper flakes. Let the sauce simmer for 10-15 minutes to thicken.
4. Combine with Pasta: Add the drained pasta to the sauce in the pan. Stir to combine, and if the mixture seems dry, add some reserved pasta water to achieve the desired consistency.
5. Incorporate the Cheese: Stir in the diced mozzarella and half of the grated Parmesan cheese until melted and evenly distributed.
6. Bake the Dish: Preheat your oven to 180°C (350°F). Transfer the pasta mixture into a baking dish, spreading it evenly. Top with the remaining Parmesan cheese.
7. Bake Until Golden: Place the dish in the preheated oven and bake for 15-20 minutes, or until the top is golden and bubbling.
8. Garnish with Basil: Once baked, remove from the oven and let it cool slightly. Garnish with torn fresh basil leaves before serving.

By following these steps, you’ll have an incredible Pasta alla Sorrentina that will delight every palate.