Melt chocolate in a double boiler on the stove. If you don’t have a double boiler, you can make one by nesting a bowl inside a pot with a shallow layer of water, allowing the water to boil gently. The water shouldn’t touch the bottom of the bowl. Watch the chocolate carefully as it melts to avoid scorching.

Pour chocolate into a freezer-safe, heat-proof bowl. Stir in tahini. Let the bowl sit out until it reaches room temperature.

Freeze the mixture until solid, around 2 hours or until you’re ready to make the truffles. If it’s frozen for overnight or longer, let the mixture warm a bit by setting in the refrigerator until the mixture is scoopable with a spoon.