Mash 2 ripe bananas and finely chop 4 strawberries. Fold fruit into batter, along with 1/2 tsp banana extract.
To frost: Whip 1 1/4 cups heavy cream with 3 tbsp confectioners' sugar. Transfer to a pastry bag fitted with a large star tip. Pipe whipped cream onto cupcakes.
Sprinkle with finely chopped walnuts and top each with a maraschino cherry.