Preheat the oven to 300 degrees. Sift together the first 4 ingredients and set aside. Heat the molasses just to the boiling point in a saucepan large enough for mixing cookies. Stir in the butter and add the flour mixture. Mix well. Drop one-half teaspoon portions of the dough onto greased cookie sheets, 2 inches apart to allow room for spreading.
Bake for 15 to 18 minutes. Remove the cookies from the oven and cool 2 minutes. Carefully slip a spatula underneath the wafers and remove them from the pan onto a cooling rack. Quickly roll each cookie around the index finger or the handle of a wooden spoon. If wafers become brittle before they are shaped, place in oven a minute to reheat, remove from pan, and roll. Store in an airtight container.
Makes about 30 cookies