Roughly chop the Amarettini. Stir mascarpone, milk and lemon juice until smooth. Stir in the Amarettini, except for something to decorate. Wash the nectarines and strawberries. Halve nectarines and remove stone.
Cleaning strawberries. Cut pineapple into cubes. Wash mint, shake dry and, except for something to decorate, pluck leaves from the stalks. Put strawberries, pineapple and mint alternately on skewers.
Grill the nectarines and skewers for about 3 minutes while turning. Fill nectarines with mascarpone cream and arrange on plates. Decorate with mint and Amarettini. Arrange strawberry skewers in 4 glasses on a ball of vanilla ice cream.