Line a 9x13 inch baking pan with parchment paper for easy removal
Melt butter and marshmallows over medium heat, stirring constantly for 3-5 minutes until smooth
Divide mixture in half and add red coloring to one half, green to the other
Add Rice Krispies cereal to red mixture and fold until coated
Add remaining cereal to green mixture and fold until coated
Press red layer firmly into pan, then press green layer on top
Cool at room temperature for 30 minutes until completely set
Optional: Decorate with white chocolate drizzle, crushed candy canes, or powdered sugar
Cut into uniform squares using a knife dipped in water between cuts
Store in airtight container for up to 5 days
