In a large bowl, cream butter and brown sugar until light and fluffy, 5-7 minutes. Beat in molasses and egg. Combine flour, ginger, cinnamon, baking soda and salt; gradually add to creamed mixture and mix well. Cover and refrigerate at least 3 hours. , Preheat oven to 350°. Shape dough into 1-in. balls; roll in sugar. Place 3 in. apart on ungreased baking sheets. Flatten to 1/2-in. thickness with a glass dipped in sugar. Bake 8-10 minutes or until set. Cool 2 minutes before removing from pans to wire racks to cool completely., For filling, in a small bowl, beat butter and marshmallow creme until light and fluffy. Gradually beat in confectioners' sugar and extract. , Spread filling on the bottoms of half of the cookies, about 1 tablespoon on each; top with remaining cookies.