• Preheat oven to 350 and line some baking sheets with parchment. In a stand mixer, cream the butter, peanut butter, vanilla, sugar, brown sugar ane salt together and mix until it is light and fluffy.
• Add the egg and mix again until fluffy, scraping down the bowl. In another bowl, whisk together the flour, baking powder, baking soda and cornstarch.
• Add the dry ingredients to the mixer and mix on low until combined. Fold in the chopped reese's cups with a baking spatula. Using a cooking scoop, scoop balls of dough onto the prepared baking sheet. If you want crumbl size you will make 9 cookies, which is almost 2 scoops with a large cookie scoop per cookie. I wanted slightly smaller cookies, so did an overfilled 1 scoop with a large cookie scoop, which made about 16 cookies.
• Form into balls and flatten them a little. Place sheets in the freezer for 15 minutes, then bake for 9-12 minutes depending on the size of the cookie. They should be baked through but just barely in the middle and not browning much on the edges. Allow to cool on the cookie sheet and then transfer to a cooling rack.

For the toppings:

• Combine the chips and oil in a heatproof bowl and microwave in 20 second increments, stirring after each, until melted. Do not overheat or it will seize up.
• Spread the melted chips on the cookies and top with chopped reese's cups. The pb topping will harden up again, so if you want it soft, these are great microwaved for 5-10 seconds before eating.