1. Prepare the Crust:

1. Heat heavy cream in a small saucepan until just simmering. Remove from heat.
2. Pour hot cream over chopped chocolate in a bowl. Let sit for 2 minutes, then stir until smooth.
3. Whisk in pumpkin spice and vanilla extract. Chill mixture for 2 hours until firm.
4. Roll chilled mixture into 1-inch balls using a melon baller or spoon.
5. Roll each truffle in sparkling sugar to coat completely. Store in refrigerator until serving.