or until the cake tests done. Cool on a rack for 15 minutes, remove cake from pan and turn right side up on a rack to finish cooling. TO MAKE SEA FOAM FROSTING: In the top of a double boiler, combine all of the ingredients, except the vanilla extract. Beat for 1 minute at high speed with an electric mixer. Place over boiling water (the water should not touch the bottom of the top half of the double boiler). Beat on high speed for about 7 minutes until the frosting forms peaks when the mixer is raised. Remove from boiling water (for the smoothest frosting, empty into a large bowl). Add the vanilla extract and continue beating on high speed until thick enough to spread, about 2 minutes. Spread on the sides and top of the cold banana cake.