Line an 8 by 4-inch loaf pan with a sheet of parchment paper long enough to cover the bottom and hang over the sides (this will act a sling to lift out the truffles once set). Add the chocolate to a medium bowl.

Combine the cream, orange peel and espresso in a small pot over medium heat. Cook until the cream is very hot, but not boiling.

Pour the hot cream mixture through a sieve over the chocolate; discard the orange peel. Let the chocolate sit, undisturbed, until it begins to melt, about 1 minute.

Stir with a rubber spatula until the chocolate is completely melted and smooth (do not whisk as this will cause air bubbles in the ganache). Stir in the sparkling wine until well combined. Pour the mixture into the prepared pan. Chill in the fridge until completely cooled and firm enough to cut (but keep in mind it’ll still be a soft, fudge-like consistency).

Add the cocoa powder to a small bowl. Lift the ganache from the tray, and cut into ½-inch bite-sized squares. Gently toss the truffles in the cocoa powder until lightly coated all over.

Store truffles in refrigerator or a cool spot (you may want to set them at room temperature 10 minutes before eating), and enjoy within one week.