Preheat oven to 350 degrees F.
Lightly grease a 9 x 13 inch pan with cooking spray or line with parchment paper.
In a large mixing bowl, beat together the butter, brown sugar, and white sugar until smooth and light.
Add the eggs one at a time, mixing after each addition. Add the vanilla.
In a separate bowl, combine the dry ingredients: salt, baking soda, baking powder, cinnamon, nutmeg, flour, and rolled oats.
Add the dry ingredients to the creamed mixture and stir until combined.
Stir in chocolate chips.
Press into prepared pan, top with flaky sea salt to taste and bake for 25 to 30 minutes or until golden brown.
Allow to cool completely before cutting.