Add butter and marshmallows to a large microwaveable bowl. Heat the mixture in the microwave at 50% power in 30 second intervals until marshmallow are mostly melted.

Add cereal to the marshmallows and stir until cereal is coated.

Pat the treat mixture into a greased 9x13.

Microwave candy melts at 50% power in 20 second intervals until mostly melted.

Stir in candy oil.

Reheat and/or add coconut oil to return melts to a pourable consistency.

Drizzle over the Cheerios treats.

Sprinkle with cinnamon.

Cut and serve.