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.

Cream the butter and sugar.,Add eggs and milk; beat well. Combine flour and soda.,Add to mixture.,______,Add vanilla. Chill 1 hour.,Roll dough 1/4 inch thick.,Cut and place 1 inch apart on greased cookie sheet.,Sprinkle with sugar (optional). Bake at 400 for 7 to 8 minutes.
Blend.