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.
Don't worry if your buttercream appears curdled after all the butter has been added; simply continue beating with the whisk attachment until it is smooth again. If you don't want alcohol in your buttercream, substitute finely grated zest of one large orange -- or more or less to taste -- for the liqueur.