Pour coconut oil and popcorn into a large rondeau (a wide, round, heavy-bottomed, somewhat shallow pot) with a tight-fitting lid, and set over medium heat. Place lid on the pot and let pot sit over heat until popcorn begins popping. Gently shake the pan until popping stops.
Combine cream, sugar, salt, and truffle oil in a mixing bowl. Pour over cooked popcorn and let steep for a few hours or even overnight.