Line a large baking sheet with Parchment paper and set aside.
Add the chocolate chips and coconut oil to a large, microwave-safe bowl.
Microwave for 20 seconds and stir to coat all the chocolate chips with the coconut oil. This will be very thick, so you'll have to work with it a bit.
Once all the chips are evenly coated with the melted coconut oil, microwave for 15 seconds, stir and repeat until the chocolate is completely smooth. Do not microwave for longer intervals thinking that it will be faster. It's necessary to stir the chocolate frequently to prevent scorching.
Add the puffed rice cereal and stir until it's completely coated and you don't see any more white on the cereal.
Transfer to your prepared pan and use the back of a spatula to press it into a thin rectangle.
Refrigerate until set, which was about 45 minutes for me.
Remove from the refrigerator and lift the entire bar out of the pan using the Parchment paper. Allow to rest on the counter for about 5 minutes before cutting.
Using a serrated knife, cut into small, rectangle size bars.
Store in a covered container at room temperature or in the refrigerator if you prefer a firmer texture.