Butter a 9x12-inch baking dish.

Melt 2 tablespoons of butter in a large nonstick pot over low heat.

Mix in the marshmallows and cranberry gelatin mix until the marshmallows have melted and the mixture is smooth.

Stir in the rice squares, oat cereal rings, mini candy-coated chocolate pieces, and dried cranberries until thoroughly combined.

Working quickly, press the mixture into the prepared baking dish and allow to cool.

Cut into 2-inch squares.