For the best texture, don't overwork the meat mixture and use parmesan that's ground to a fine powder (use the food processor or the rasp side of a box grater). For more heat, add 1/2 to 3/4 teaspoon dried crushed red pepper to the sauce. Breadcrumbs should come from a crustless French or country-style loaf of bread. The best ground beef to use is 85% lean and an immersion blender would be great to have for this recipe.