In a bowl place your icing sugar, orange zest and juice and combine fully. Set on one side. Soak the gelatine leaves in cold water until bloomed.
In a saucepan, bring the cream, mascarpone and vanilla paste to a simmer. Add the sugar mixture and dissolve completely.
Once the mixture has just boiled, set aside to cool slightly.

Squeeze out any excess water from the gelatine and stir into the warm mixture until fully dissolved.
Pour the mixture into your chosen container and let this set for about 4 hours for a soft set, or overnight for a more ferme consistency.