Melt coconut oil with peanut butter and honey in a medium sized saucepan set over medium heat. Stir until mixture is smooth and combined.
Remove from heat and stir in vanilla, salt, hemp hearts and brown rice cereal. Mix until all of the ingredients are combined.
Using a spatula, evenly distribute cereal mixture in an 8x8 inch square baking dish lined with parchment paper. Place in fridge to chill for 10 minutes.
Meanwhile, melt chocolate in a microwave-safe bowl in 30 second increments, until chocolate has melted. Stir when you check the chocolate to prevent it from burning to the bottom of the bowl.
Pour the melted chocolate over the cereal mixture and spread to evenly distribute it.
Sprinkle with coconut if desired. Place in the freezer for 15-20 minutes, or until the chocolate firms up.
Once firm, lift the parchment paper with the cereal mixture out of the pan and cut into 16 bars.