For the mascarpone topping, add a little sugar to the fruit pulp according to taste. For unsweetened fruit pulp, stir in about 150g of sugar; for sweetened, omit some sugar.
Mix mascarpone with powdered sugar until light and fluffy. Stir yogurt with fruit sauce and lemon juice until smooth.
Add the yogurt mixture to the fluffy mascarpone and continue beating until it is easy to pipe.
Garnish cupcakes, muffins and co. with the mascarpone topping as desired.