Step 1

In a large saucepan, melt butter over medium heat. Stir in marshmallows and cinnamon. Mix well to combine and make sure all of the marshmallows are melted. This should be a liquid consistency.

Step 2

Place Rice Krispies in a large mixing bowl and add the melted marshmallow mixture over the top. Using a greased rubber spatula, mix well to combine by folding it over itself in the bowl until no more loose Rice Krispies can be seen.

Step 3

Press into parchment-lined 9x13 baking pan. Make sure it's even across the top, so no high spots, and let cool for 30 minutes.

Step 4

While cooling, make icing by mixing all ingredients together well to combine.

Step 5

Cut Cinnamon Roll Rice Krispie treats into 12 equal sections, and drizzle with icing.