In a saucepan over medium heat, melt the butter until it turns golden brown and has a nutty aroma. Remove from heat and let cool slightly.

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

In another bowl, combine the browned butter, brown sugar, and granulated sugar. Mix until smooth.

Add the egg and vanilla extract to the butter mixture and whisk until combined.

Gradually add the dry ingredients to the wet ingredients and mix until just combined.

Preheat the oven to 350?F (175?C) and line a baking sheet with parchment paper.

Scoop tablespoon-sized balls of dough onto the prepared baking sheet, spacing them about 2 inches apart.

Sprinkle each cookie with flaky sea salt.

Bake for 10-12 minutes or until the edges are lightly golden. Let cool on the baking sheet for a few minutes before transferring to a wire rack.