Marshmallow Filling: Whip cream; stir in vanilla extract and marshmallows.
Cake: Measure flour. Add cocoa, baking powder and salt to flour. Stir to blend.
Beat eggs and vanilla with mixer until light. Add sugar gradually. Continue to beat
until light and fluffy. Add blended dry ingredients to egg mixture with electric
mixer (low speed). Add boiling water. Mix well. Pour into greased, wax paper lined
10 x 15-inch jellyroll pan.
Bake at 400 degrees F for 15 to 18 minutes.
Loosen edges and turn out of pan immediately onto tea towel sprinkled with confectioners'
sugar. Remove wax paper. Turn rough edges from cake. Roll up carefully in tea towel.
Cool on rack.
Unroll cooled cake. Spread evenly with Marshmallow Filling. Roll up carefully.