Ice Cream Cake Roll

3 eggs
1 cup sugar
1/3 cup water
1 teaspoon vanilla
3/4 cup flour
1 teaspoon baking powder
1/4 teaspoon salt
1/4 cup cocoa
Powdered sugar
1/2 gallon ice cream (might require slightly less)

Heat oven to 375.  Line jelly roll pan (15 1/2 x 10 1/2 x 1 inch) with aluminum foil and grease generously.  Beat eggs in a small mixer bowl on high speed until very thick and lemon colored, about 5 minutes.  Pour eggs into large mixer bowl.  Beat in sugar gradually.  Beat in water and vanilla on low speed.  Add flour, baking powder, salt and cocoa gradually beating just until batter is smoorth.  Pour into pan.  Bake until wooden pick inserted in center comes out clean, 12 to 15 minutes.  Immediately loosen cake from edges of pan; invert on kitchen towel sprinkled generously with powdered sugar.  Carefully remove foil.  Trim off stiff edges if necessary.
While hot, carefully roll cake and towel from narrow end.  Cool at least 30 minutes. Unroll cake, remove towel. Spread with softened ice cream.  Roll up again, wrap in foil, and freeze.