Preparation time: 40 minutes plus cooling time
Cooking time: 15 minutes

2 x 85g/3oz packs watercress, finely chopped
3 egg yolks
2 tbsp parmesan cheese, grated
4 egg whites
100g/4oz mascarpone cheese
2 sticks celery, finely chopped
100g/4oz frozen cooked prawns, thawed and chopped
salt and black pepper

Pre-heat the oven to 190°C, Mark 5 and line a 23 x 33cm (9” x 13”) swiss roll tin with baking parchment. Mix the watercress, egg yolks and parmesan cheese together and season with salt and pepper. Whisk the egg whites until stiff and fold into the watercress mixture. Pour into the tin and bake for 10-15 minutes until well risen and springy to the touch. Leave until cold.

Mix the mascarpone, celery and prawns together and spread carefully over the roulade. Roll it up from the short side, peeling the parchment back as it rolls. Serve cold with watercress salad.