The dough should be well-chilled before baking. You can either start a day early and chill overnight, or start preparing 1-2 hours before the cookies will be needed.
In a heavy pot, combine the molasses, sugars, spices and water. Turn the heat up and bring the mixture to a boil while stirring frequently.
Add the butter to the mixture (in pads or chunks) and remove the pot from the heat. Continue stirring the mixture until the butter has melted and the mixture is uniform in consistency. Pour the hot mixture into a large mixing bowl. In another bowl, combine the flour, corn syrup, egg and baking soda and whisk until well-blended. Combine with the hot mixture and stir until the dough has formed. Place the dough on a lightly floured board and knead for 1-2 minutes. Wrap the dough in waxed paper and chill until the dough is firm (1-2 hours or overnight).
On a lightly floured board, roll the dough out to about 1/8 inch in thickness (the thinner, the crisper) and either cut into shapes or make round cookies about 2 inches in diameter. Put the cookies on a lightly greased cookie sheet.
Preheat the oven to 375 degrees F and bake for 8-10 minutes until they are golden brown. Remove the cookie sheet from the oven and place them on a wire rack to cool.