In a large mixing bowl, combine butter, brown sugar, sugar, peanut butter, and eggs, beating on low, until blended.

In a medium bowl, combine flour, baking soda, salt, and oats.

Add the dry ingredients to the wet ingredients in the mixing bowl, and beat until combined.

Fold in the peanut butter chips and Reese’s pieces.

Chill the dough for at least 2 hours, or ideally overnight.

When ready to bake, preheat oven to 325°F.

Line baking sheets with parchment paper or silicone baking mats.

Drop dough by rounded tablespoonful onto cookie sheets.

Bake for 10-14 minutes, or until edges are golden brown, and centers are set. Repeat with remaining dough until all cookies are baked.

Remove to wire racks to cool completely.