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.
½ cup smooth peanut butter, ½ cup butter, ½ cup brown sugar, ⅓ cup granulated sugar, 1 egg at room temperature, ½ teaspoon vanilla extract
Add in the flour baking powder, baking soda, corn starch, and salt, and mix just until the flour mixture disappears.
1 & ⅓ cup all-purpose flour, ½ teaspoon baking powder, ½ teaspoon baking soda, 1 tablespoon corn starch, ¼ teaspoon salt
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 chocolate mixture, 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!
⅔ cup milk chocolate chips, 2 teaspoon oil