1.Halve nectarines; cut each half into thirds.
2.In a medium frying pan, melt butter; add sugar and nutmeg, stir until sugar dissolves. Add nectarines; cook, stirring, until browned lightly.
3.In a small bowl, combine mascarpone, icing sugar, liqueur and rind.
4.Cut each brioche into four slices; toast until browned lightly both sides.
5.Divide brioche slices among serving plates; top with mascarpone mixture and nectarine pieces. Dust with extra sifted icing sugar.