– Brown butter in a medium saucepan over medium-low heat stirring constantly until the butter gets foamy and releases a nutty aroma (approx. 7 minutes). – Once browned bits begin to form on the bottom, remove pan from the heat, pour butter into a heat-safe bowl and place in the freezer to chill for 10 minutes. – Preheat oven to 350 degrees. Line an 8x8 metal baking pan with parchment paper. – In a medium-sized bowl, whisk together oats, flour, baking soda, and salt. – In a separate bowl, beat chilled browned butter, brown sugar and granulated sugar with an electric mixer until light and creamy — approx. 3 minutes. – Beat in egg, vanilla and milk. – Stir dry ingredients into wet. – Spoon cookie dough into baking pan then use your fingers to press into an even layer. – Bake for 18 to 20 minutes or until the edges turn golden and the center is set. – Cool  completely before adding peanut butter.