Step 1
Sift together the flour, cocoa powder, baking powder, baking soda and salt. In the large bowl of a standing mixer, beat the butter on medium speed until creamy and light in color, about 3 minutes. Add the sugar in a steady stream, continuing to beat for 2 minutes. Add the egg, vanilla and espresso mixture. Continue beating, scraping down the sides of the bowl as needed, then mix in the melted chocolate.