Start by tearing crustless white bread into pieces and place them in a bowl. Pour 2/3 cup of cold water over the bread, letting it soak for about 5 minutes until it’s fully absorbed and softened. Using a fork, mash the soaked bread into a smooth mixture to ensure even texture in your meatballs.

In a large mixing bowl, combine the ground beef, sweet Italian sausage, grated Parmesan cheese, minced garlic, sea salt, black pepper, and the mashed bread mixture. Crack in a large egg to bind everything together. Mix thoroughly using your hands, until all ingredients are well blended to create a flavorful filling for your meatballs.

Shape the mixture into 1.5-inch meatballs, ensuring they are uniform in size for even cooking. Lightly dredge each meatball in all-purpose flour, shaking off any excess. In a large skillet, heat a drizzle of light olive oil over medium heat, then sauté the meatballs for about 6 minutes, turning occasionally until they are golden brown on all sides. Remove them and set aside.

In the same skillet, add chopped yellow onion and sauté over medium heat until the onions are soft and translucent, around 5 minutes. Stir in minced garlic and cook for an additional minute, allowing the aroma to fill your kitchen.

Pour in the crushed tomatoes and optional bay leaves, carefully stirring to combine with the sautéed onions and garlic. Gently return the browned meatballs to the skillet, ensuring they are nestled among the sauce. Allow everything to simmer uncovered on low heat for 30 minutes.

While the sauce simmers, bring a large pot of salted water to a boil. Add the spaghetti and cook according to the package directions until al dente, typically around 8-10 minutes. Once cooked, drain the spaghetti in a colander, but save a splash of pasta water just in case you need to loosen the sauce later.

In a large serving bowl, toss the drained spaghetti with the marinara sauce and meatballs until evenly coated. Serve hot on a large platter, garnished with extra Parmesan cheese and fresh basil.