Preheat oven to 375°F and line cookie sheets with parchment paper.

In a saucepan, brown the butter over medium heat until golden and nutty.

In a bowl, mix brown sugar, rolled oats, egg, and vanilla extract. Stir in the cooled brown butter.

Add salt and flour, mix gently until fully incorporated.

Scoop rounded tablespoons of dough onto the prepared cookie sheets.

Bake for 6 minutes or until edges are golden brown. Cool on baking sheet for 5 minutes before transferring to a wire rack.