Beat the yolks until thick and light. Gradually add in the sugar. Add in the water, and beat well.
Alternately add in the sifted dry ingredients and the beaten egg whites.
Spread the cake batter in a 15x10x1 inch jelly roll pan that has been greased and lined with parchment.
Bake in a preheated 350 degree oven for about 20 minutes or until the cake is done.
Turn out immediately on a slightly dampened cloth sprinkled with powdered sugar.
Remove the parchment, and trim any crusty edges.
Spread with the marshmallow filling and roll up immediately.
Sprinkle with powdered sugar. Drizzle with chocolate icing if desired.
For the Marshmallow Filling
Stir the egg white, sugar, water, and cut marshmallows in the top of a double boiler. Cook over hot water while beating with an egg beater until the mixture stands in peaks, about 10 minutes.
Remove from heat and add in the vanilla extract and baking powder.
Beat 5 minutes more or until the icing is of smooth spreading consistency.
For the Thin Bitter Chocolate Icing
Melt the chocolate in a double boiler. Remove from heat, and cool slightly.
Boil the water and sugar together for 5 minutes until a thin syrup develops.
Slowly pour the hot sugar syrup into the melted chocolate, beating constantly. When slightly thick, spread or drizzle on the Chocolate Roll.