position rack in center of oven and preheat oven to 325.Line 2 baking sheets with parchment paper.
Mix together the flour, ginger, cinnamon. cloves, nutmeg, baking soda and salt onto a sheet of waxed paper or foil
In a large mixing bowl beat together butter, shortening, and brown sugar on low speed just until combined then increase to medium speed and beat until fluffy and smooth, about 5 minutes. Add the egg, beat well then then the molasses
Add half of the flour mixture and half of the buttermilk to the batter.Add the remaining flour and buttermilk and beat until just combined
Spoon 2 tablespoons batter 2 inches apart on parchment lined baking sheets.Bake one sheet at a time about 10=12 minutes until the pies springe back when pressed gently. Remove from the oven and let the cakes cool on the sheet for 5 minutes before transferring to a rack to cool.
Spread filling evenly on half of pies, top with other half to sandwich filling between
In a large bowl, beat butter with confectioners sugar on low,increasing to medium until mixture is crumbly, about 1 minute.Add the heavy cream and vanilla and beat until light and fluffy. Use as filling for the whoopee pies