Put the apple into a saucepan with 2 tbsps water and the sugar. Heat gently, then simmer until the apples are completely soft and mushy. Leave to cool, then puree with the ginger and ginger syrup.
Whip the cream until it holds soft peaks. Carefully mix the apple puree, cream, custard and maple syrup together and chill.
Serve in individual glasses, drizzled with maple syrup.