Chocolate fondue is immediately gratifying. In the time it takes to make the sauce, you can peel the clementine oranges. It's also a great reason to keep a supply of candied grapefruit peel and glaceed orange slices on hand.
Bring cream and butter to a simmer in a small saucepan. Pour over chocolate in a bowl.
Let chocolate mixture stand for 3 minutes, then whisk until smooth. Whisk in liqueur. Serve immediately with clementines and candied citrus.