Set the oven to 350 F.
In one bowl, mix together the flour, baking soda, salt, nutmeg and cardamom.
In another bowl, use an electric mixer to cream together the butter and sugar until light and fluffy, 3 to 5 minutes. Add the egg and mix for another minute. Add the vanilla and mix again.
Carefully add the flour mixture to the butter mixture and mix until you have a smooth, uniform dough.
Use your hands to form the dough into a long log. Wrap the dough log in plastic wrap and refrigerate for 20 minutes or up to a day if you want to make cookies tomorrow.
When ready to bake, split the dough into 24 pieces. (Or more likely do it in batches of 12!) Roll each piece into a ball and place them, 6 at a time, onto a well greased or parchment-lined cookie pan. It's good to do just 6 per baking sheet because these guys will spread out a bunch and they need room. Bake for 10 minutes on the center rack. If you want to do 2 batches at once you can, but when you pull out the tray on the center rack, move the one on the top rack down and bake for one more minute. Continue until you have baked all the cookies.
Let the cookies cool on the pan once they come out of the oven for about 2 minutes. As you remove them, sprinkle them with a little bit of kosher salt, if using. They will seem gooey, but they will harden up as they cool. Once they are no longer too soft to move, place the cookies on a wire wrack to cool completely.
Eat right away or store in a sealed container.