Heat chocolate chips in a double boiler* on medium-low heat until melted (about 10 minutes), while stirring with a rubber spatula. Once heated, add to food processor with avocado and pulse until smooth.
Chill for 2 - 3 hours in the refrigerator. Remove from refrigerator and use a spoon to scoop out and roll into balls (approximately 2 Tbsp. each).
Add cocoa powder to a small bowl. Roll each truffle in coco powder to coat and store truffles in the fridge for up to 3 days. Remove from fridge about half hour before serving.
Notes
*If you don't have a double boiler, place a rimmed bowl into a saucepan that has an inch or two of water in it so that the bottom of the bowl is a few inches above the water. Heat chocolate in the bowl.