Brown the Butter: Melt unsalted butter in a medium saucepan over medium heat. Swirl frequently for 5-7 minutes until it turns deep amber and smells nutty. Remove from heat and cool slightly.

Mix Sugars: In a large mixing bowl, combine packed brown sugar and granulated sugar. Add warm brown butter and whisk until smooth and fluffy.

Incorporate Wet Ingredients: Stir in maple syrup, large egg, and vanilla extract until fully combined for a glossy texture.

Combine Dry Ingredients: Whisk together flour, baking soda, and salt in a separate bowl. Gradually fold into the wet mixture until just combined.

Chill Dough: Cover the dough and refrigerate for at least 30 minutes.

Preheat Oven: Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.

Scoop Dough: Form dough into balls, spacing 2 inches apart on the baking sheet.

Sprinkle Salt: Generously sprinkle flaky sea salt on top of each cookie dough ball before baking.

Bake: Bake for 10-12 minutes until edges are golden brown but centers are soft.

Cool: Let cookies rest on baking sheet for 5 minutes before transferring to a wire rack.