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.

Preheat oven to 350 degrees.,Cream butter and sugar until fluffy.,Add eggs, beating well after each one.,______,Add the sifted dry ingredients alternately with the sour cream.,Pour into 2 greased 9x5x3 inch loaf pans.,Bake at 350 degrees for 40 to 45 minutes.

Add mashed bananas.