Bring water, butter, peanut butter, and oil to a boil. Remove from heat and add all ingredients. Stir until well blended. Pour into a greased & floured jelly roll pan. Bake at 400 degrees for 20 minutes. Cool (or not)...works well either way.
FROSTING: Bring to boil: 1 stick butter, 1/3 cup milk, 1/2 cup peanut butter, 1 tsp. vanilla. Remove from heat and add 1 box (1 pound) SIFTED powdered sugar. Beat with mixer until smooth. Spread on cake.