Put the raisins into a saucepan and cover with water. Boil for five minutes. Drain well. Add the butter and stir until melted. Add sugar and stir. Add the eggs and mix well. Put aside while preparing the tart shells.
Preheat the oven to 400 degrees. Make tarts shells using store-bought pie dough or your own dough. Cut circles to fit muffin tins. (Hint: cut strips of parchment paper to put under the tart shells. Use the paper to help lift the baked tarts out of the muffin tins.) You can use phyllo dough or phyllo dough tart shells. Fill the unbaked shells almost to the top with the raisin filling. Bake about 15-20 minutes.
These tarts freeze well!