In a medium bowl, combine flour, baking soda & powder, and salt. Set aside.
Add the butter and peanut butter to the bowl of a mixer. Beat until fluffy, then beat in sugars. Add milk, egg and vanilla and continue beating. Then add the flour mix ½ at a time and mix until everything is combined well.
Fold in Reese's Pieces with a rubber spatula.
Drop heaping tablespoon sized balls of dough on a parchment lined cookie sheet. Lightly press a fork on the tops, making a crosshatch pattern.
Bake 10-15 minutes, until cookies are barely browned on the bottom edges. Don't overbake! Let cool on the pans a few minutes, then transfer to a wire rack.
Recipe by Flying on Jess Fuel at https://www.jessfuel.com/double-peanut-butter-cookies/