Cream together the butter and sugar in a large mixing bowl - it should be creamy colored and airy. A hand blender or stand mixer works well for this. This helps the cookie become fluffy and chewy.
Gently incorporate the eggs to the butter mixture one at a time.
In a separate bowl, sift together all the dry ingredients.
Add the dry ingredients to the wet by adding a little at a time and folding or gently mixing the batter together. Keep going until you've incorporated all the remaining flour mixture. The dough should be a beautiful green color.
Chill the dough for at least an hour - up to overnight. The longer the better!
Preheat your oven to 325 F.
Roll the dough into balls the size of ping pong balls and place them on a non-stick cookie sheet.
Bake them for 12-15 minutes until the bottoms just start to become golden brown and the cookie no longer looks wet in the middle. Note: you can always bake them at 350 F for a less moist, fluffy cookie. It will bake faster by about 2-4 minutes 350 F so watch them closely.