Put butter in a large pot and melt.

Add the marshmallows to the melted butter. Stir till marshmallows are smooth and hot.

Add rice krispies. Stir until well mixed. You can add food coloring, chocolate chips, or any addtition of your choice here now and be sure it is well mixed

Remove from heat. Select a baking dish and coat with spray oil. Pour mixture into a container or baking dish. And flatten with the back of spoon.