Sift dry ingredients together twice. Mix together Miracle Whip, cold water, and egg. Add to dry ingredients and beat well. Add vanilla if desired. Bake at 350 degrees for 35 minutes. When cool spread with filling. For filling, cook together dates and water for five minutes. Cool completely then spread on cake. For frosting, melt chocolate and butter together in double boiler. Remove from heat and beat well until thick enough to spread. Add the nuts and spread over filling on the cake.