Combine, in the top of a double boiler, the cut-up Snickers bars, water, and peanut butter; heat and stir until well melted and blended. COOL. Mix together the flour, baking soda and salt. Set aside. In a large bowl, cream butter thoroughly; gradually add sugar and beat until fluffy. Beat in 4 unbeaten egg yolks and add vanilla; beat in the cooled candy bar mix, mixing until smooth and adding quarter cup buttermilk. Stir in the flour mix alternately with the remaining 1 cup buttermilk; mix only until blended. Gently fold in 4 stiffly beaten egg whites. Divide batter evenly between 2 greased and floured 23 cm SQUARE pans and bake in preheated 180ºC F oven for 10ºC 55 minutes. Cool in pans on rack for 5 minutes, turn out, and finish cooling on rack. Serve with sweetened whipped cream. ----