In a large pot, melt the marshmallows and butter. Stir until smooth. Remove from heat and add the cinnamon and Rice Krispies. Stir until completely blended. If the mixture seems too wet and sticky to work with, add a little more Rice Krispies.
Lay out a piece of waxed paper on the counter. Spray clean hands with cooking spray. Shape the krispies mixture into 12 oval shapes. (Re-spray hands while working with the cereal mixture, as needed). Place the shapes on waxed paper.
Mix the powdered sugar with a little bit of water to create a "glue." Use the sugar-glue to attach eyes to each oval. Spoon a little sugar glue onto where you'd like the eyes to be, then place two cranberries on top of the 'glue.' Let set for about an hour.
Wrap the mummies. *Don't add the gauze before allowing the mummies to set or you'll end up with gauze sticking to the marshmallow treat! Starting at one end of the gauze, wrap around the mummy head to cover it entirely, leaving a peek hole for the eyes (as shown in the photo). Use a small piece of tape to fasten, or press the other end of the gauze gently into the head to stick. Store in an airtight container until ready to serve.