Step 1

Pit and peel the avocados and scoop the flesh into a blender or food processor. Add the lime zest and juice, and process until really smooth.

Step 2

Add the cream cheese and blend until completely combined. Season with salt and pepper. Transfer to a bowl.

Step 3

Sprinkle the gelatin over 2 tbsp of water in a small heatproof bowl. Let stand about 5 minutes until the mixture looks spongy. Place the bowl in a skillet of barely simmering water and stir constantly until the gelatin dissolves.

Step 4

Drizzle the dissolved gelatin over the avocado mixture, and stir well. If using, beat the egg white until soft peaks form. Fold the egg white into the avocado mixture.

Step 5

Spoon into four 4oz (100ml) ramekins. Cover with plastic wrap and refrigerate 2 hours, or until chilled and set. Serve chilled.