Preheat oven to 350°. In a large bowl, beat the egg and vegetable oil. Gradually add the sugar and continue beating until pale yellow in color. In another bowl, sift together the flour, cocoa, baking soda and salt. In a measuring C, combine the buttermilk and vanilla extract. While mixing, alternate adding the dry ingredients and buttermilk to the egg and sugar, beginning and ending with the dry ingredients. Fold in mini chocolate chips. Drop the batter by heaping TBSP onto greased or silicon lined cookie sheets. 6-8 per sheet. Bake for 10 minutes. Remove to wire racks to cool. When cool, spread filling between two cookies to make whoopie pies.

In a small bowl, dissolve the malted milk powder in the boiling water. In a medium saucepan over medium heat, stir together the milk, cream, and malted milk mixture. Whisk in the flour and stir constantly until the mixture comes to a boil and has thickened, 2 minutes. Remove from heat. Transfer the mixture to a medium bowl, to speed cooling process. Whisk vigorously for about 1 minute to release excess heat and set aside to cool to nearly room temperature. In the bowl of a standing mixer fitted with the paddle attachment, beat the butter and confectioners’ sugar on medium speed until pale and fluffy, about 3 minutes. Turn the mixer to low and pour in the cooled milk mixture. Increase the speed to medium and continue beating until the filling is fluffy and stiff peaks start to form.  If mixture is warm, chill in refrigerator for 15 minutes, then beat until stiff peaks form.  Fill cookie halves with 1-2 TBSP of the filling, top with other cookie.  Makes about 12 filled cookies.