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.

Saute onion and celery in 2 tablespoons margarine.,Stir in tuna, soup, mayonnaise, milk and mushrooms.,Cook noodles and drain.,Combine all in 2-quart greased casserole.,Top with bread crumbs topped with margarine.,______
Bake at 350 for 25 to 30 minutes.