Line a large baking sheet or plate with wax paper, parchment paper, or paper towels and set it aside. In a large bowl, add the Rice Chex cereal and set aside. In a small bowl, combine the sugar and ground cinnamon to make the cinnamon sugar mixture and set aside.

Melt the unsalted butter in a microwave-safe bowl or on the stovetop. Immediately pour the melted butter over the bowl of Rice Chex cereal, stirring gently to ensure all the cereal pieces are evenly coated with butter.

Microwave the butter-coated cereal for 2 minutes, stopping to stir after 1 minute. Next, add half of the cinnamon sugar mixture, stir very well, then add the second half and stir again thoroughly to evenly coat every piece. Microwave the mixture for another 1 minute. I like to give it an extra good stir here so that the cinnamon sugar sticks to every bit of cereal for even flavor.

Pour the coated, hot cereal onto your prepared lined sheet or plate, spreading it out into a single layer to ensure even cooling. Let it cool completely before serving or storing. Once cool, store the cereal in an airtight container for up to 5 days. For a little extra texture, sometimes I crush a handful of the finished pieces before serving for more crunchy bits!