Step 1

Beat sugar and butter together with electric mixer for 2 minutes..

Step 2

Add egg whites one at a time, beating on low speed for about 30 seconds after each.

Step 3

Add sour cream, milk, vanilla and extracts and beat on low speed for about 1 minute.

Step 4

In separate bowl combine dry ingredients.

Step 5

Add to wet ingredients gradually, and beat lightly after each addition.

Step 6

Fill lined muffin tins 2/3 full.

Step 7

Bake at 400 degrees for 5 minutes and then reduce heat to 350 degrees and bake additional 8-10 minutes, or just until cake springs back when lightly touched in center.

Step 8

After 5 minutes remove cupcakes from pan and allow to cool completely on wire rack before frosting.

Step 9

Blend butter and cream cheese until fluffy.

Step 10

Stir in extract, zest and and sugar and stir until smooth.