Given the task definition and input, reply with output. In this task, you will be presented with the directions of a recipe separated by "," and have to fill in the "___" which is a step that is missing from the recipe.

Cook spaghetti; drain.,Combine eggs and Parmesan.,Stir into spaghetti.,Layer 1/2 spaghetti and 1/2 Mozzarella twice in a 9 x 13-inch pan.,Bake at 350 for 10 minutes.,Brown ground beef; drain well.,______,Heat while spaghetti is baking. Pour sauce over baked spaghetti.,Let set 10 minutes before serving.
Add spaghetti sauce.