Preheat the oven to 350º and line heavy baking sheets with parchment paper.

Melt the butter and add to the bowl of your stand mixer - or if using a hand mixer, add to a mixing bowl.

Beat in the dark brown sugar, then the egg, then the vanilla and lemon zest.

In a smaller bowl, whisk together the flour, salt, baking powder and baking soda.

Beat the flour mixture into the butter mixture until completely incorporated - a minute or so should do it.

Place 1/2 cup or so of the sugar in a small bowl.

Portion the dough with a small cookie scoop - tablespoon size.

Roll each cookie into a round ball between the palms of your hands, and then roll in the sugar until coated and place on the baking sheet, leaving 2 inches between each cookie.

Bake for 10 to 11 minutes. Cookies will still be on the pale side and very soft. Cooking them longer will result in a crunchy, rather than chewy cookie.

Allow the cookies to cool on the baking sheet for a 4 or 5 minutes so that they have time to set. Remove to a cooling rack and cool completely before storing in a tightly sealed container.

They will keep at room temperature for up to a week.