Preheat the oven to 350?F. In a large bowl, beat the butter, sugar, and brown sugar until smooth. Beat in the egg and molasses.
Add the flour, baking soda, cinnamon, ginger and salt. Stir by hand or beat on low speed just until well blended and smooth.
Roll the dough into balls about the size of a walnut. Put some sugar in a small dish, and roll each ball of cookie dough in the sugar.
Put the balls on a parchment-lined sheet and bake them for 12-14 minutes, until they are cracked and golden around the edges. Move them onto a wire rack to cool. Makes 2 1/2 dozen cookies.