Dissolve the entire packet of gelatin in cold water and let it sit for 30 minutes. Wash the peaches and cut them into halves. Peel half of the halves, remove the pits and puree them. Heat the gelatin on low heat. Add the liqueur to it and mix well.
While stirring add the pureed peaches. Remove from the heat . Beat the cream with the powdered sugar and add them to the peaches with gelatin. Pour this into a suitable container (i.e. cake form) and put it in the refrigerator for 4-5 hours to set.
Remove the dessert from the refrigerator and decorate with the remaining peach halves, cut into slices. Finish decorating with some cream to form roses.