Combine raisins and 1 tablespoon flour; stir well, and set aside.
Cream butter; gradually add sugar, beating well. Add pumpkin, milk, molasses, and eggs, beating well.
Sift together flour, baking powder, salt, and spices; add to creamed mixture, stirring just until dry ingredients are moistened. Stir in raisins.
Spoon batter into greased muffin pans, filling full. Bake at 375° for 20 minutes.