Combine first 4 ingredients in bowl. Sift dry ingredients together.
Add them & the water to creamed mixture. Beat till well-blended.
Bake at 325 degrees (I used an 8 inch square pan) for 35 minutes. For cupcakes, bake at 350 degrees for 15 minutes.To make the frosting, melt the butter and place in a microwave safe bowl.
Add the cocoa powder and stir until smooth.
Add the confectioner’s sugar and sour cream alternately to the chocolate mixture and beat until fluffy. Beat in the vanilla.