Mix 5 cups of OREO O's® cereal and ½ cup mini marshmallows in a large mixing bowl and set aside. Melt 6 tablespoons of butter.
Once the butter has melted, add in 4 cups of mini marshmallows and stir until mixture is smooth.
Combine OREO O's® cereal mix with marshmallow butter mix and stir until combined. Add ¼ cups sprinkles and lightly fold into mixture.
Line and grease a 9 x 9 inch glass pan.
Pour mixture into pan and spread out evenly. Top with additional sprinkles to your liking.
Allow bars to harden for about 1 hour before cutting into 16 even squares. Remove from pan before decorating.
Decorate by melting 1 cup of blue candy melts (or white chocolate) and placing in a piping bag (or zip lock bag with the corner cut off). Drizzle melted candy over the top of the bars and top with additional sprinkles to your liking.
Allow candy coating to dry before serving.
Enjoy!