Red Velvet Whoopie Pies

Red velvet cake, once a minor curiosity, is now ubiquitous in American bake-shops. It is a trend that outlasted its trendiness. Though most closely identified as a Southern recipe, the red velvet probably originated somewhere in the Northeast as a cocoa powder- and buttermilk-based cake. In theory, the cocoa powder reacts with the baking soda to create a reddish hue, but somewhere along the way, the red quotient began to be upped with an unhealthy dose of red dye. Unfortunately, a rash of b