Preheat oven to 350°F. Beat butter and brown sugar together until light and fluffy, then add egg, vanilla and molasses and beat again to combine. Sift dry ingredients together, and add slowly to wet mixture, blending well between additions. Place granulated sugar in a small bowl (for rolling the cookies in).
Roll walnut-sized balls of dough in the sugar, and place on a parchment-lined baking sheet, about two inches apart. If the dough seems too soft to roll into balls, place the bowl in the fridge for about 15 minutes to firm up the dough.
Bake for about 10 minutes, or until cookies seem set but not browned. When baked, let cookies cool for a couple of minutes on the cookie sheet, then transfer them to a rack to cool. Makes about 24 cookies.