Start by preheating the oven to 350F and then prepare a baking sheet by lining it with parchment paper. Set it aside.

In a bowl, combine the butter, peanut butter, brown sugar, and granulated sugar. Mix in the eggs and vanilla extract until well combined.

Incorporate the flour, baking powder, baking soda, corn starch, and salt into the mixture. Stir until just combined, then gently fold in the roughly chopped Reese’s peanut butter cups.

Using a large cookie scooper, portion out the dough into 9 equally sized balls. Roll them between your palms, flatten them to about 1 inch, then freeze the dough discs for 15 minutes.

Bake the cookies in the preheated oven for 12-13 minutes.

In the microwave, melt the peanut butter chips with the oil in 30-second intervals, stirring in between each time.

Once the cookies are out of the oven, generously drizzle each with the melted peanut butter chips, ensuring it covers the surface. Sprinkle the chopped Reese’s cups on top. Allow the cookies to cool completely on the baking sheet before serving.