Prep: 20 min.
Bake: 15 min. + cooling
2 tablespoons butter, softened
3/4 cup sugar
1 egg white
1/2 cup plus 2 tablespoons buttermilk
1/3 cup water
1 tablespoon white vinegar
1 teaspoon vanilla extract
1-1/2 cups all-purpose flour
1/4 cup baking cocoa
1 teaspoon baking soda
1/2 teaspoon salt
1/3 cup miniature semisweet chocolate chips
In a large bowl, beat butter and sugar until crumbly, about 2
minutes. Add egg, then egg white, beating well after each addition.
Beat on high speed until light and fluffy. Beat in the buttermilk,
water, vinegar and vanilla. Combine the flour, cocoa, baking soda
and salt; beat into batter just until moistened. Stir in chocolate
Fill muffin cups coated with cooking spray three-fourths full. Bake
at 375° for 15-18 minutes or until a toothpick inserted in the
muffin comes out clean. Cool for 5 minutes before removing from pans
to wire racks.