Preheat oven to 350. Line a 9x13 inch baking dish/pan with nonstick foil and spray with cooking spray.
Melt butter in a medium sauce pan over medium-high heat. Continue to cook 3-5 minutes until butter becomes a dark amber/golden color, and remove from heat. While butter is browning, add coconut flakes to a medium pan and cook over medium-high heat 3-5 minutes stirring throughout. When the flakes begin to brown, remove from heat. (Careful not to let them burn)
In a large bowl combine browned butter, brown sugar, eggs, and vanilla and mix until smooth. Add toasted coconut flakes and mix again until smooth. In another medium bowl combine flour, baking powder, 1 teaspoon salt, and oats and whisk to combine. Gradually stir flour mixture into wet ingredients until all ingredients are incorporated. Stir in 1 tablespoon milk to help bring mixture together. Gently stir in butterscotch chips.
Press mixture into prepared pan and bake for 20-25 minutes until mixture is set and top looks dry. Immediately after removing from the oven, sprinkle with remaining 1/2 teaspoon sea salt. Allow to cool completely before cutting into bars and serving. Store in airtight container.