1) Mash the grapes and press through a fine sieve.
2) In a saucepan, simmer the juice until reduced to half.
3) Peel and core pears, then poach in the grape juice in batches and remove in a glass serving dish.
4) Pour rest of the grape juice over the pears and refrigerate.
5) Garnish with a little ground mace and serve with sweet heavy or dairy sour cream.