Peel, halve lengthwise, and drizzle the banana with the lemon juice. Beat the cream with the powdered sugar until stiff, and fill into a piping bag with star-shaped tip. Coarsely chop the chocolate, and melt over a hot water bath.
Lay 1 halved banana in an oblong desser bowl, place 3 scoops of ice cream in the center, and decorate with a dollop of whipped cream. Serve garnished with cocktail cherries and the chocolate sauce.