1. Shell the prawns and place them in a salad bowl. Peel and dice the mango and add to the prawns. Peel and slice the bananas and sprinkle with the lemon juice to prevent discoloration.
2. Add to the mayonnaise the mango chutney, sugar, cognac and Tabasco. Whisk the cream lightly and add. Blend all the ingredients well.
3. Mix the sauce gently into the fruit and prawns.
4. Place the lettuce leaves in a dish, and top with the salad mixture. Refrigerate until ready to serve.