1. Preheat your oven to 190°C or 375°F.

2. Cook the dried pasta according to the package instructions until it's al dente, then drain and set it aside.

3. In a large skillet, sauté the diced onions and minced garlic over medium heat until they're softened.

4. Add the ground meat to the skillet, breaking it apart with a spoon as it cooks.

5. Stir in the tomato puree, salt, black pepper, and vegetable bouillon cubes. Bring the mixture to a simmer and cook for 10 minutes.

6. Add the crushed tomatoes, sugar, dried oregano, and dried basil to the skillet. Stir well to combine all the ingredients.

7. In a large mixing bowl, combine the cooked pasta, meat mixture, and chili flakes if you're using them. Mix everything together until it's well combined.

8. Transfer the pasta mixture to a baking dish and top it with the meatballs.

9. Bake the gratin in the preheated oven for 25-30 minutes, or until the top is golden brown and the meatballs are cooked through.

10. Remove the dish from the oven and garnish it with fresh basil leaves. Serve hot and enjoy!