Cream the margarine and the sugar together. Add the egg, baking powder, spices, salt, vanilla, and half the flour, and mix well. Gently fold in the remaining flour. Divide the batter evenly among the muffin tins, and place a few blackberries on the top of each.
Bake 20-30 minutes (longer for jumbo muffins). Allow to cool for 5-10 minutes before removing from tins. Cool on a rack.
Recipe courtesy of Gingerich Farms