Preheat the oven to 350F.
Line two baking sheets with parchment paper or silpat mats.
Add the butter and sugar to the bowl of a stand mixer fitted with the paddle attachment and beat on medium speed until it is well combined-- about 1 minute.
Next add in the peanut butter, egg, and vanilla and mix to combine.
Stir together the flour and baking soda and powder in another small mixing bowl then beat into the wet ingredients on low speed, just until no large lumps of flour remain.
Fold in the chocolate chips and chopped Reese’s cups.
Once well incorporated, scoop out the dough and shape into 1” balls. Flatten the balls with a fork, if desired.
Bake until the edges begin to turn golden brown-- about 13-15 minutes.
Transfer to a wire rack to cool slightly before enjoying.
Store in an airtight container at room temperature for up to 5 days.