Sift flour, baking powder and salt together. Beat eggs until thick and light; beat in 0.75 cup sugar gradually. Add flour mixture all at once; blend gently. Melt chocolate; stir in the water, soda and the remaining sugar until smooth. Add to the batter quickly. Pour into greased waxed paper-lined 15x10 inch jelly roll pan. Bake for 18 to 20 minutes at 180ºC Invert the cake on a towel sprinkled with confectioners sugar; remove paper. Trim cake edges. Roll towel and cake; cool for 30 minutes. Beat Dream Whip with milk and mint flavoring until stiff peaks form; beat in food coloring. Unroll cake, discarding towel. Spread cake with Dream Whip. Roll cake again; frost with Dream Whip. Chill until ready to serve.