3/4 cup plus 2 tablespoons whole-wheat pastry flour, (see Ingredient Note)
1/2 cup granulated sugar
1/3 cup unsweetened cocoa powder
1 teaspoon baking powder
1 teaspoon baking soda
1/4 teaspoon salt
1/2 cup nonfat buttermilk, (see Tip)
1/2 cup packed light brown sugar
1 large egg, lightly beaten
2 tablespoons canola oil
1 teaspoon vanilla extract
1/2 cup hot strong black coffee
Confectioners’ sugar, for dusting
Preheat oven to 350?F. Coat a 9-inch round cake pan with cooking spray. Line the pan with a circle of wax paper.
Whisk flour, granulated sugar, cocoa, baking powder, baking soda and salt in a large bowl. Add buttermilk, brown sugar, egg, oil and vanilla. Beat with an electric mixer on medium speed for 2 minutes. Add hot coffee and beat to blend. (The batter will be quite thin.) Pour the batter into the prepared pan.
Bake the cake until a skewer inserted in the center comes out clean, 30 to 35 minutes. Cool in the pan on a wire rack for 10 minutes; remove from the pan, peel off the wax paper and let cool completely. Dust the top with confectioners? sugar before slicing.