Add chocolate chips to a medium bowl. Set aside.
Melt butter, heavy cream, and nutella over medium heat. Once melted, bring to just under a boil (you should see little bubbles around the edges but don't wait for big bubbles across the surface), stirring constantly.
Let cool for 30 seconds then pour over chocolate chips. Let sit for 1 minute, then whisk mixture until smooth.
Cover bowl with plastic wrap and refrigerate for 1 to 2 hours or until firm.
Scoop heaping teaspoons or tablespoons (depending on how large you want the truffles) and form into balls. Roll in cocoa powder or powdered sugar, then roll one half in sea salt. Another option would be to sprinkle sea salt over the tops of the truffles and press very gently with a finger to make sure it sticks.
Place in freezer for 10 minutes to set. Keep in refrigerator until ready to eat.