Prepare the Filling:

1. In a saucepan set over medium-low heat, combine the marshmallows, 1/2 cup sherry and pineapple juice. Cook, stirring occasionally, until melted. Remove from heat.
2. In a small bowl, sprinkle gelatin onto remaining 4 tbsp sherry. Stir until combined. Add to the hot marshmallow mixture, stirring until the gelatine is completed dissolved. Set aside to cool.

Make the Crust:

1. In the meantime, prepare the crust by mixing together the graham cracker crumbs, butter and sugar in a large mixing bowl. Press the mixture evenly into the bottom of a lightly greased 8" springform pan.
2. Once the marshmallow mixture has cooled to room temperature, gently fold in the whipped cream. Pour the mixture into the prepared crust, smoothing off the top with a spatula.
3. Garnish with pineapple slices and maraschino cherries in a decorative pattern. (It might be tempting to skip the topping, please don't... it not only gives the cake its mega-kitsch flair, but also provides a much-needed dose of acidity that keeps the cake from being overwhelmingly sweet).
4. Chill for at least 1 hour before serving to allow the filling to set completely. Before serving, run a knife along the edge of the cake and then carefully unlatch and remove the springform.