Combine the ground beef, finely chopped onion, minced garlic, egg, breadcrumbs, grated Parmesan cheese, dried oregano, and a pinch of salt and pepper in a large mixing bowl. Mix thoroughly until all ingredients are well incorporated.

Shape the mixture into small meatballs, approximately 1-inch in diameter.

Heat a small amount of oil in a large frying pan over medium heat. Add the meatballs and cook until they are browned on all sides and fully cooked, which should take about 10-12 minutes. Remove the cooked meatballs from the pan and set them aside.

In the same pan, add the canned chopped tomatoes, tomato paste, sugar, and a pinch of salt and pepper. Stir the ingredients together and bring them to a simmer. Allow the sauce to cook for roughly 10 minutes, letting it thicken.

While the sauce is simmering, prepare the spaghetti according to the package instructions until it reaches the al dente stage. Drain the cooked spaghetti and set it aside.

Once the tomato sauce has thickened to your liking, return the cooked meatballs to the pan. Let them simmer for an additional 5 minutes, allowing the meatballs to absorb some of the sauce's flavours.

To serve, place the spaghetti on plates, top it with the meatballs and the tomato sauce. Finish by garnishing with fresh basil leaves.