Line an 8x8-inch square baking dish with parchment paper.
Place the chocolate in a large bowl and microwave on 50% power in 30-second increments, stirring after each, until completely melted (alternately, you can melt the chocolate in a double boiler on the stovetop).
Immediately stir in the cereal until evenly coated and distributed. Pour the mixture into the prepared pan and smooth into an even layer. Refrigerate until set, about 30 minutes. Remove from the pan and place on a cutting board. Cut into bars or irregular shapes. The bars can be stored in an airtight container in the refrigerator for up to 1 month.