Preheat oven to 400 degrees F.
In a large bowl, add beef, sausage, bread crumbs, cheese, garlic, herbs, eggs, salt, and pepper. Stir together until combined. Roll meat mixture into 2-inch sized meatballs.
In a large, heavy pot heat olive oil over medium-high heat. When the oil shimmers, add meatballs in batches. Do not crowd. Brown well on bottoms before turning or meatballs will break apart. Continue cooking until browned all over. Remove meatballs to a plate that has been lined with paper towels, as each batch is finished.
Place meatballs on a large baking sheet and bake for 10 minutes or until meatballs are cooked all the way through. Remove from oven.
Place a large pot of water on to boil for spaghetti. When it boils, add salt and pasta and cook to al dente.
While the spaghetti is cooking, put meatballs in a large pot and cover with your favorite marinara sauce. Heat over medium-low heat.
When the spaghetti is done cooking, drain and place in a large serving bowl. Top with meatballs and marinara sauce. Garnish with Parmesan cheese and chopped fresh basil, if desired. Serve immediately.