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 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 of an inch then freeze the cookie dough discs for 15 minutes.
Bake the cookies in the preheated oven for 12-13 minutes
Melt the chocolate chips with the oil in the microwave in 30-second increments, mixing in between every time.
Generously top each hot cookie with the melted peanut butter chips, spread it all around, then top each cookie with the 3 muddy buddies. Let the cookies cool down fully on the baking sheet then enjoy!