Place chocolate in a glass or metal bowl, set aside.
Bring wine to a boil in a small saucepan, reduce heat to medium-low and simmer until reduced to ¼ cup, 9-10 minutes. Add cream, butter, vanilla, and salt to simmering wine, cook until butter has melted and bubbles start to form around the edges of the pan, about 2 minutes.
Pour wine-milk mixture over chocolate, cover with plastic wrap and let sit 5 minutes.
Gently stir ganache until smooth and completely incorporated. Transfer ganache to an 8-inch square baking dish and spread into an even layer. Let sit at room temperature for 1 hour, then cover and refrigerate until firm and scoopable, about 1 hour.
Roll truffles in cocoa then transfer to an airtight container and store in refrigerator.
Bring to room temperature before enjoying.