You don't have to add the rum topping. These are very good either way.
If you want an extra bite of mincemeat, you can make a mincemeat center. To do this, add 1/3 cup of the batter to the bottom of the muffin cup, then add a generous tablespoon of mincemeat, then top off with the remaining 1/3 cup of batter. Bake as directed above.