Preheat oven to 300ºF (~149ºC). Line two large baking sheets with parchment paper or silicone mats.
In a large bowl, mix the cereal, coconut, egg whites, and powdered sugar together.
Drop tablespoons full of the mixture onto the baking sheets. Because the egg whites are quite sticky, it is a lot easier to transfer the mixture from the spoon to the baking sheet with damp hands. I ran my hands under water many times while performing this step.
Bake for about 25 minutes, or until the coconut starts to brown.
When there is about a few minutes left in the baking time, melt the chocolate. Put the chocolate chips in a microwave-safe bowl and microwave it for 60 seconds. Check the progress of the chocolate. If you can still see whole morsels, continue microwaving at 15-second increments. Keep microwaving until most of the chips are partially melted and soft. Stir the chocolate together until it turns into a fairly runny sauce.
Using a spoon, drizzle the chocolate on top of the cooked macaroons.The drizzle should harden in a few hours.
Store leftover macaroons in an airtight container in room temperature.