Preheat oven to 350 degrees F. Line a cookie sheet with a silicone baking mat or parchment paper.
In the bowl of your stand mixer cream the butter and peanut butter until combined. Add the sugar and brown sugar, mix till light and fluffy. Incorporate the eggs (one at a time) and vanilla.
In separate bowl combine flour, oats, baking soda, baking powder, and salt. Add dry ingredients slowly to mixer until combined. Fold in Reese’s Pieces.
Place dough in fridge for one hour. Roll dough into the size of a small golf ball. Press down slightly on cookie sheet. Bake for 8 to 10 minutes. Let cool on wire cookie rack. Store in airtight container on countertop, enjoy!