Move oven racks to middle and lower middle positions, and preheat oven to 350 degrees F. Line baking sheets with parchment paper or silicone baking mats.
In a medium bowl whisk together the flour, baking powder, baking soda, and salt, and then set aside.
In the bowl of a stand mixer beat together the the peanut butter, butter, shortening, honey, and both sugars until light and fluffy, about 2 minutes. Add the eggs and vanilla and beat until well incorporated, about 30 seconds.
Gradually add in the flour mixture and beat on low speed until fully incorporated. Use a rubber spatula to fold in the Reese's Pieces and mini peanut butter cups.
Using a 4-tablespoon scoop, scoop cookie dough and place the dough 2 inches apart onto the prepared baking sheets.
Bake for 11-12 minutes, rotating pans half-way through baking.
DO NOT over bake the cookies! The cookies will just start to look a little golden around the edges. Remove cookies from the oven and let them sit on the baking sheets for 4-5 minutes. Then remove them from the cookie sheets and place them on a cooling rack. Cool the cookies completely, and store them in an airtight container.