Optional decoration: Red sugar, gold sprinkles, white or milk chocolate for drizzling, cinnamon
Set aside 6 oz of chocolate in a microwave-safe bowl with spices.
In a small saucepan, gently heat cream and vanilla until tiny bubbles appear around the edges.
Pour cream evenly over chocolate; let stand 4 minutes without stirring. Stir gently until incorporated. If it doesn’t all melt after a minute, microwave the whole bowl in 10-second intervals. Allow to cool at room temperature until fairly solid.
Cover a baking sheet with parchment paper. Scoop firm ganache into chunks and roll into 3/4-inch balls with your hands. If the ganache gets too squishy, put it in the freezer for 10 minutes. Refrigerate ganache balls for 30+ minutes.
Melt the remaining 6 ounces chocolate in the microwave (use 50% power and 30-second intervals) or in a double boiler. Dip ganache balls into melted chocolate and replace on baking sheet.
Allow truffles to mostly set (about 5 minutes in the fridge) before garnishing. Top with colored sugar or sprinkles, roll in cinnamon, or drizzle with melted white or milk chocolate.