Bring the butter to a boil in a saucepan over medium high heat. Swirl the pan a few times. The butter will bubble then foam. Once the foam subsides, swirl the pan and you will see brown flecks. The butter will have a nutty, toasty aroma. Remove the pan from the heat and transfer to a heat proof container. Let cool to room temperature.
In a large bowl, whisk together both flours, the baking powder, baking soda, salt and cinnamon.
In the bowl of a stand mixer fitted with the paddle attachment, beat the cooled brown butter on medium speed with the granulated and brown sugar until smooth, about 2 minutes. Add the eggs, peanut butter and vanilla. Beat on medium high speed until well combined, about 1 minute. Scrape down the sides of the bowl and the paddle as needed.
Add the flour mixture to mixer bowl, beat on low until combined. Mix in the oats. Mix in the chocolate chip medley.
Transfer the dough to a clean work surface covered in plastic wrap. Divide the dough into two portions and pat them into disks. Wrap each separately in the plastic wrap. Cool the dough in the fridge for at least 30 minutes up to 4 days. This dough will become very firm if chilled over 1 hour. Remove from the fridge 30 minutes before using it.
Preheat the oven to 350˚ Fahrenheit with the racks in the middle. Line two baking sheets with parchment or silicone liners. Place 2 tablespoon portions of dough 3 inches apart on the baking sheets. Bake for 12-14 minutes or until slightly golden brown on top.
Let the cookies cool a few minutes on the baking sheets then transfer to cooling racks.