Add the extra thick double cream, mascarpone and icing sugar to a bowl. Using an electric whisk, start to mix everything together.

You want to stop when it starts to thicken up and is able to hold its own shape, this only takes a couple of minutes on a medium speed. Be careful not to overmix as this can result in a grainy icing.

Using a small sieve, such as a tea strainer, strain the juice from the passion fruit pulp into the mascarpone icing. Set the seeds aside. Reserve a small amount of the juice and seeds for decoration if required.

Using a spoon, lightly stir through.

Now you're ready to ice your cake.

Place any spare icing in a pot and cover with cling film. Store in the fridge for up to a week.