In a saucepan over medium heat, melt unsalted butter, stirring frequently, until golden brown and nutty-smelling, about 5-7 minutes. Let cool for 5 minutes.

In a mixing bowl, whisk together all-purpose flour, baking soda, and salt.

In another bowl, beat the cooled brown butter with granulated sugar and light brown sugar until smooth and creamy. Add in the egg and vanilla extract, mixing until fully combined.

Gradually add the dry mixture into the wet ingredients, mixing until just combined.

Scoop the dough into tablespoon-sized balls, optionally dip in sprinkles, and chill in the fridge for at least 30 minutes.

Preheat your oven to 350°F (177°C). Place the chilled cookie dough balls on parchment-lined baking sheets and bake for 12-13 minutes or until edges are lightly browned.

Let cool on the baking sheets for 5 minutes before transferring to a cooling rack.