Pour milk and cream into a tall mixing bowl. Add cream powder and mix briefly with the whisks of the hand mixer on the lowest setting. Then whip at highest setting for 3 minutes. Chill for at least 1 hour.
Cream the sour cream and a little egg liqueur with the whisk of the hand mixer. Gradually stir in the remaining liqueur. Finely crumble the Amarettini. Drain the peaches, cut them in half and cut them in a fan shape
Pour the mousse into a piping bag with a large star-shaped spout. Pipe small tuffs onto dessert plates and spread the liqueur cream all around. Sprinkle with some liqueur. Decorate everything with peaches, amarettini crumbs and cocoa
Instead of egg liqueur you can also mix the sour cream with Baileys liqueur or without alcohol with vanilla sauce