Combine cocoa and boiling water, stirring until smooth; set aside until cool.
Cream butter, gradually add sugar, beating well at medium speed. Add eggs, one at a time, beating well after each addition.
Combine dry ingredients in a medium bowl, add to creamed mixture alternately with the cooled cocoa mixture, beating at low speed, beginning and ending with the dry ingredients. Stir in vanilla. Do not overbeat.
Pour batter into 3 buttered and floured 9-inch round cakepans. Bake at 350 degrees for 20 - 25 minutes or until a cake tester inserted in center comes out clean. Cool in pans 10 minutes, remove from pans and cool completely on wire racks.