Liberally butter the bottom and sides of a 9 x 9-inch non-stick baking dish with softened butter. Set aside. (Tip: You may also line the dish with aluminum foil first, then butter the foil to make the bars easier to remove when set.)
In a heavy bottomed deep saucepan cook together 1/2 cup butter, sweetened condensed milk, white chocolate chips and cinnamon chips. Simmer stirring constantly over low heat until melted.
Add the marshmallows. Continue to cook stirring until the marshmallows have completely melted.
Remove the saucepan from the heat and add the cereal. Quickly stir until the cereal pieces are completely coated. Press evenly into the pan.
Allow to set for at least 4 hours to cool or overnight before cutting.
Cut into 48 (1)-inch squares.
Store tightly sealed chilled or at room temperature.