Follow these straightforward steps to make delicious spaghetti and meatballs:

1. Preheat Oven: Preheat your oven to 400°F (200°C).

2. Make the Meatballs: In a large bowl, combine the ground beef, ground pork, breadcrumbs, grated Parmesan cheese, chopped parsley, egg, minced garlic, salt, pepper, and Italian seasoning. Mix until just combined, then form meatballs about the size of golf balls.

3. Bake the Meatballs: Line a baking sheet with parchment paper. Place the meatballs on the baking sheet and bake in the preheated oven for 20-25 minutes, or until browned and cooked through.

4. Prepare the Marinara Sauce: In a large skillet, heat olive oil over medium heat. Add chopped onion and cook until softened, about 5 minutes. Stir in minced garlic and cook for an additional minute until fragrant.

5. Add Tomatoes: Pour in the crushed tomatoes and stir to combine. Follow with sugar, salt, pepper, basil, oregano, and red pepper flakes if using. Bring the sauce to a simmer.

6. Simmer the Sauce: Reduce heat to low and let the sauce simmer while the meatballs are baking, stirring occasionally.

7. Cook the Spaghetti: In a large pot, bring salted water to a boil. Add spaghetti and cook according to package instructions until al dente. Drain and set aside.

8. Combine Meatballs and Sauce: Once the meatballs are done baking, add them to the simmering marinara sauce. Let them cook together for about 10 minutes, allowing the flavors to meld.

9. Serve: To serve, place a portion of spaghetti on each plate and top with meatballs and sauce. Garnish with grated Parmesan cheese and fresh basil leaves.

10. Enjoy: Serve hot and enjoy the incredible taste of homemade spaghetti and meatballs!