Line muffin pans with paper liners.
Preheat oven to 350.
Stir together flour, salt and baking powder.
Cream together butter and sugar until fluffy.
Mix in eggs, root beer extract and vanilla.
Gradually add in flour and root beer until just combined.
Fill each cup about 2/3 full.
Bake for 15-20 minutes or until toothpick inserted in center comes out clean.
Cool in pan for 10 minutes before transferring to wire rack to cool completely.
Whip butter, root beer extract and vanilla for frosting until fluffy.
Gradually add powdered sugar.
Add root beer until you reach desired consistency.
Transfer to piping bag and frost each cupcake.
Top with a cherry and cut straw (optional).