Whoopie Pies With 7 Minute Frosting - cooking recipe

Ingredients

Cake
1 egg
1/3 cup vegetable oil
1 cup caster sugar (superfine)
2 cups unsifted all-purpose flour
1/2 cup dutch process cocoa
1 teaspoon baking soda
3/4 teaspoon baking powder
1/4 teaspoon salt
3/4 cup milk
1 teaspoon vanilla
Filling
1 1/2 cups sugar
1/4 teaspoon cream of tartar
1/8 teaspoon salt
1/3 cup water
2 large egg whites
1 1/2 teaspoons pure vanilla extract

Preparation

Cake:
Heat oven to 350\u00b0F.
Grease two large cookie sheets or line 2 baking sheets with parchment and set aside.
In a large bowl with mixer at medium speed sugar and vegetable oil. Gradually beat in beat egg and continue beating until pale yellow in color. In another bowl, combine flour, cocoa, baking powder, baking soda and salt. In a measuring cup combine milk and vanilla. Add flour and milk mixtures alternately to eggs and sugar, beginning and ending with dry ingredients. Drop by tablespoons onto cookie sheet. These will spread a lot, so make 6 cakes per sheet at a time. Bake about 5 minutes or until top springs back when lightly touched with finger. Remove to wire racks to cool. When cool, use filling and two cakes to make sandwiches.
Filling:
Place sugar, cream of tartar, salt, water, and egg whites in the top of a double boiler. Beat with a hand held electric mixer for 1 minute. Place pan over boiling water, being sure that boiling water does not touch the bottom of the top pan. (If this happens, it could cause your frosting to become grainy). Beat constantly on high speed with electric mixer for 7 minutes. Beat in vanilla.