Make the batter: Combine the flour and baking soda. Set aside. In the bowl of a mixer fitted with the paddle attachment, “cream” the butter with the sugars until smooth, 8-10 minutes until light and fluffy. Do not rush this step. Add the egg, salt, and vanilla and beat until blended. Remove the bowl from the machine and stir in the flour mixture and chocolate.
Bake the cookies: Drop spoonfuls of dough onto a nonstick baking sheet, leaving space between each, as they will “spread” as they cook. Bake until light brown on the tops and edges, 8-10 minutes. Remove and allow the cookies to “firm up” a little, 5-10 minutes, before serving.