Preheat oven to 350 degrees and line a large baking sheet with a silpat liner or parchment paper.

Place butter into a small saucepan over medium-high heat. Melt and let bubble until brown bits form at bottom of pan and butter turns a golden brown color. Takes 5-8 minutes generally. Remove from heat and let cool for 15 minutes before using in recipe. You can stick in the freezer for 5 minutes to cool quickly.

Place brown butter and sugar into a stand mixer, beating until combined. Add egg, vanilla and peanut butter until combined. Slowly add flour, salt, baking soda and chocolate chunks mixing on low until combined. With a cookie scoop, scoop dough onto prepared baking sheet 1 inch apart. Bake for 10-12 minutes, until baked through. Remove from oven and let cool for 10 minutes before transferring to cooling rack. Serve warm or room temperature.