• Preheat the oven to 350F then line a baking sheet with parchement paper and set aside.
• Cream the butter, peanut butter, brown sugar, and granulated sugar. Add in the eggs and vanilla extract then mix until combined.
• Add in the flour, oats, baking powder, baking soda, corn starch, and salt, and mix just until the flour mixture disappears.
• Using a large cookie scooper, scoop out 9 equally sized cookie dough balls, roll them in between the palm of your hand, then gently flatten them to about 1 inch in thickness and bake in the preheated oven for 12-13 minutes.
• Let the cookies cool down on the baking sheet for 15 minutes before transferring to a cooling rack.

Make the cream cheese frosting

• Cream the butter, cream cheese, and vanilla extract together until smooth. Mix in the powdered sugar until combined.
• Sift in the cocoa powder, then add in 2 tbsp milk and mix again until fluffy. If the frosting seems too thick, add in one more tablespoon of milk.
• Frost each cooled down cookie with a thick dollop of frosting, chill for 30 minutes or more, then enjoy!