The Batter Station is a station in Papa's Cupcakeria. First, select the liner the customer desired. Then, select the batter. When you fill the liner with batter, you will get a message on how you did. At first, you will have to fill one cup at a time, but later on in the game, you can get an upgrade that will let you fill both cups simultaneously. Getting both cups with a "PERFECT!" bubble will get you 100% for the station.
If you filled the cup with too much or too little batter, you will get a message about that and if you serve them to the customer you will lose points.