Preheat the oven to 350 degrees and line a baking sheet with parchment paper.
In a large mixing bowl, whisk the oats and baking soda together. Set aside.
In a separate bowl, beat the butter, sugar, and brown sugar together until creamy.
Add the eggs and vanilla and beat until smooth.
Add the peanut butter and beat until well combined.
Pour in the oat mixture and stir to combine.
Fold in the mini chocolate chips and half of the Reese’s Pieces.
Use an ice cream scoop to place the dough onto the baking sheet two inches apart from each other and press down on the top of the dough ball lightly with the back of the scoop.
Press the remaining Reese’s Pieces and mini peanut butter cups into the tops of the cookies.
Bake for 15 to 18 minutes or until the bottom of the cookie is golden brown but the center is still soft.
Allow to cool completely on the baking sheet. Enjoy!