Mix the 200ml Rubicon watermelon juice drink with the Marsala or sherry in a shallow dish. Line up 4 serving glasses. One by one, dip the sponge fingers into the liquid, soaking them for a few seconds and then put them into the glasses, breaking them to fit. Pour any remaining liquid into the glasses.
Reserve some of the strawberry slices and watermelon for decoration. Mix the remainder with the raspberries and then share them between the serving dishes.
For the topping, beat the mascarpone cheese with a wooden spoon until softened, then mix in the 4 tablespoons Rubicon watermelon juice drink, stirring until smooth. Spoon onto the trifles and chill until required. Serve, decorated with the reserved fruit and mint leaves.
Cook’s tip: Use different fruits if you like, such as blueberries and mango instead of the strawberries and raspberries.