Preheat oven to 350F. Beat egg whites until foamy. Stir in buttermilk, prunes and vanilla. Set aside. In a large mixing bowl, combine cocoa and baking soda; add boiling water and stir until mixture thickens. Stir in egg-white mixture until smooth. Add sugar and flours; blend completely. Stir in peanut butter chips. Pour batter into a 13x9 inch baking pan lightly ocated with nonstick cooking spray. Bake for 30 min. Let cool before cutting. Recipe By : Shape Dec 1994