Melt butter in a large skillet over medium heat.
Add Cheerios and stir well to coat in butter.
Continue cooking and stirring for about 5 minutes until Cheerios turn golden and crispy.
Remove from heat and transfer to a large bowl.
In a small bowl, mix sugar and cinnamon together.
Sprinkle the cinnamon-sugar mixture over the warm Cheerios and toss to coat evenly.
Let cool slightly and enjoy!