In a large pan, add marshmallows and butter. Heat on medium low until butter melts.
Remove from heat and stir until marshmallows melt and mixture is smooth.
Fold in cereal.
Press mixture into baking dish. Cover with cling wrap and press down. Allow to chill for 2-3 hours before cutting.
Cut into 1βx6β bars. Melt the chips by heating in the microwave in a microwave safe bowl in 30 second bursts until melted and smooth. Drizzle onto the cereal bars and serve.