Beat eggs very lightly and add the sugar gradually, beating after each addition. Add 1/4 cup cold water. Sift flour, cocoa, baking powder, and salt together. Add egg mixture, beating slowly. Flavor with vanilla. Line a greased 15 1/2 x 10 1/2 1 inch jelly-roll pan with wax paper and grease again. Pour in the batter, spread smooth, and bake in a 425 degree oven for 12-15 minutes. Turn out on a towel sprinkle with confectioners' sugar. Remove wax paper and trim crisp edges. Roll up in a towel. Cool. Unroll and spread with coffee or vanilla ice-cream softened enough to spread. Roll up quickly, wrap in foil, and keep in freezer until ready to serve. Slice and serve.