Preparation

• In a small saucepan, bring the cream to a boil over medium heat.
• In a large mixing bowl, pour the cream over the chocolate, stirring with a wooden spoon or silicone spatula until the mixture is smooth. Stir in the butter. Stir in the Cognac and vanilla extract. Cover with plastic wrap and refrigerate until firm, about 2 hours.
• Put the cocoa powder in a shallow bowl. Remove the chocolate mixture from the refrigerator and, using hands wet with cold water or two teaspoons, form it into 1-1/2-inch balls. Roll the truffles in the cocoa powder to coat. Place several at a time in a fine-mesh strainer and gently shake to remove excess cocoa powder. Let sit at room temperature for 15 minutes before serving.

Make Ahead Tips

The truffles can be stored in an airtight container at room temperature for up to three days.