First make the syrup: mix the lemon juice and sugar in a small pan and simmer for 5 minutes, making sure the sugar dissolves completely. Stir in the Grand Marnier.
Prepare the fruit for the fruit salad and toss in the syrup. Cut the pineapple in half vertically, including the leaves. Scoop out the flesh from each pineapple half with a grapefruit knife, ensuring that the flesh remains in one piece.
Put the fruit salad with the syrup in the pineapple shells. Slice the pineapple flesh and the red apple, dipping the red apple slices in lemon juice to prevent discolouration, then arrange alternate slices of pine- apple and red apple on top of the fruit salad in the pineapple shells. Serve fresh cream separately.