These Rainbow Rice Krispie Treats are a fun and colorful twist on classic Rice Krispie treats, packed with the fruity flavor of Fruity Pebbles cereal and the magical marshmallows from Lucky Charms cereal. Soft, gooey, and full of bright color, this no bake cereal treat recipe comes together quickly and makes the perfect St. Patrick’s Day dessert or fun treat to share with the family.