Whoopie Pies

Adapted from Gourmet Magazine, January 2003

1. For the cakes:
   Preheat oven to 177°C (350°F). Line baking sheets or jelly roll pans with parchment paper.

2. Place all cake ingredients except for milk into the bowl of a food processor with a steel blade. Process until the butter is well distributed and mixture is very thick; scrape down sides as needed. While running the machine, gradually add the milk through the chute in the lid until a smooth batter forms. Remove blade, scrape it and the sides of the container. Using a small cookie scoop, transfer portions of batter, which have been leveled off with a blade, to the lined baking sheets.

3. Bake in upper and lower thirds of oven, switching position of sheets halfway through, until tops are puffed and cakes spring back when touched, 11 to 13 minutes. Transfer with a metal spatula to a rack to cool completely.

4. For the filling:
   Measure milk into a saucepan. Stir in Wondra or sifted flour. Using a whisk, cook on medium heat until thick. Remove pan from heat and cool to room temperature.

5. In the bowl of a stand mixer, cream together butter and shortening. Add salt, sifted confectioners sugar and vanilla. Mix until all ingredients are incorporated. With mixer on slow speed, add the cooled flour mixture 15 ml  (1 tablespoon) at a time. Beat on medium high for 3 – 4 minutes or until mixture has a fluffy-creamy texture.