Sift flour, baking soda, spices, and salt into a bowl and set it aside.
Cream the butter and sugars on medium spee for several minutes until smooth, light, and fluffy.
Beat in the egg, then molasses, and mix again. The dough will start turning a lovely brown color.
Mix in the flour mixture one-third at a time. Turn out the dough on a lightly floured surface. Roll the dough into two 9-inch logs. Wrap in foil and refrigerate for at least 30 minutes, or until firm enough to slice.
Grease several cookie sheets. Using a sharp knife, cut sliced 1/4 to 3/8 inch thick. Place on cookie sheet and sprinkle the tops with additional sugar.
Bake at 350F for 6 to 10 minutes, until set but not browned. Cool sheets for a few minutes before moving cookies to a wire rack.
Once cooled, sandwich two gingersnaps with a small dollop of marshmallow fluff. Dip in melted chocolate that has been cooled slightly.