Melt butter and mix in sugar. Let mixture cool and then add egg. Add soda, molasses, salt, and ginger. Stir in thoroughly. Add flour and mix in. Chill the dough for at least 1 hour (Overnight is even better)
When the dough has chilled, preheat the oven to 375.
Roll the dough into walnut-sized balls with your hands. Roll the dough balls in white sugar. Place them on greased cookie sheets. Flatten them with a spatula.
Bake at 375 for 10-12 minutes or until nicely browned. Cool on cookie sheets for no more than 1 minute, and then remove tthem to wire racks to finish cooling. (if you leave these on cookie sheets for too long, they'll stick.)