Line the base of a 25cm tart tin with a removable base with baking paper.

Add the biscuits to a food processor and blitz to a fine crumb. Add the melted butter and a pinch of salt and blitz again until it resembles damp sand. Tip into the tart tin and press evenly over the base and up the sides. If feels like it won’t come together but it does. Take your time here - the more compact it is, the better it will hold together. I like to use the base of a glass to really compress it. Freeze for 10 -15 minutes to set.

Remove the vanilla gelato from the freezer about 15 minutes before using so it softens slightly. Spoon into a bowl and give it a
quick mix, then spread evenly over the chilled base. Return to the freezer for about an hour, or until firm.

Take the mango gelato out of the freezer 15 minutes before you need it. Once softened, give it a mix in a bowl, then spread it evenly over the set vanilla layer, using a knife or spatula to smooth the top. Freeze again until firm. This can be up to 5 days.

About an hour before serving, decorate the top with mango slices. I like to start from the outside and work my way in, but do whatever feels easiest. Return to the freezer one last time for 30 minutes to 4 hours, just to set.

Serve straight from the freezer.