1cupReese's Pieces(the minis for baking or regular size both work)
Instructions
Preheat the oven to 350℉. Line baking sheet(s) with parchment paper.
In a large bowl, using an electric handheld mixer on medium speed, mix the softened butter, brown sugar, and white sugar until combined. Add the egg, egg yolk, vanilla, and peanut butter and beat on high speed until fluffy.
Add the flour, baking soda, cream of tartar, and salt and mix on low speed just until combined. Fold in the chocolate chips and Reese's Pieces.
Scoop the dough by teaspoonful onto the prepared baking sheet, placing each cookie 2 inches apart. Top with additional Reese's Pieces and chocolate chips, if desired. Bake in the preheated oven for 8-12 minutes or until puffy and no longer wet-looking on top. Let cool on the baking sheets for 10 minutes before transferring to a wire rack to finish cooling. Finish baking the remaining cookies. Enjoy!
Notes
Store finished, cooled cookies covered at room temperature.