Cocoa krispie treats

1 10-oz bag of marshmallows
2 Tbsp butter
3 Tbsp unsweetened cocoa
Partial bag of Heath bar morsels ( ½ to ¾ cup; I used the rest of a bag that was left over from something else)
8 cups cocoa krispies

Oil an 8×12″ or 9×13″ pan by pouring 1-2 Tbsp of vegetable oil in the bottom of the pan and spreading around with a paper towel. In a huge microwave-proof bowl (as large as your microwave oven will accommodate), melt the marshmallows and butter on low checking every minute or so until melted. Stir with a wooden spoon. Add cocoa and stir. Add Heath bar morsels and stir. Gently stir in the cocoa krispies until thoroughly incorporated. Using your dominant hand inside a plastic sandwich bag, scoop the krispie mixture out of the bowl into the pan and push the mixture around until it is evenly distributed in the pan. Let sit for several hours. Invert the pan onto a flat surface such as a cookie sheet. Using a sharp knife, cut into squares.