Place a rack in the center of the oven and preheat the oven to 350 degrees F. Line two cupcake baking pans with 12 paper linings each (24 paper linings in total)

In a small bowl, combine both off the flours and give it 1 good whisk. Do not overmix.

In another small bowl, combine the buttermilk and sour cream and whisk until combined.

In the bowl on an electric mixer, fitted with the paddle attachment, cream the butter until smooth. Add the sugar gradually and beat until fluffy, about 3 minutes. Add the eggs, 1 at a time, beating well after each addition. Add the vanilla bean paste, and let it mix into the batter. Add the dry ingredients in 3 parts, alternating with the buttermilk-sour cream mixture. With each addition, beat until the ingredients are incorporated but do not over beat. Using a rubber spatula, scrape down the batter in the bowl to make sure the ingredients are well blended. Carefully spoon the batter into the cupcake liners, filling them about 3/4 full. Bake for 20 to 25 minutes, or until a cake tester inserted into the center of the cupcake comes out clean. Let the cupcakes cool in the pan for 10 minutes before moving to a wire rack to complete cooling.

In the bowl of an electric mixer, fitted with the paddle attachment, cream the butter for 3 -4 minutes until it's fluffy add the confectioners sugar, vanilla extract, and meringue powder. Let the ingredients mix for 2 - 3 minutes. Add the tablespoon of milk, if the frosting is too thick add an additional tablespoon. Pipe the frosting using a 1M piping tip or use a knife to spread frosting on cupcakes.