I don't have an actual recipe, but a nice fluffy Chocolate Mousse made with liqueur and piped in with a pastry bag star tip would be nice. Maybe find a recipe on the internet, and add some Grand Marnier or Creme de Menthe,-if you used the CdM you could crush some candy canes and sprinkle on top. White Chocolate Mousse would be really pretty that way..
I just looked and this one sounds easy, made with Kahlua. Take note of the amount suggestion for the Kahlua, says it won't set right if you use too much. This is probably one you just pour in and it's not piped in like I was describing above.
EASY CHOCOLATE - KAHLUA MOUSSE
1 (6 oz.) pkg. semi-sweet chocolate pieces
2 1/2 tbsp. Kahlua (don't use more or it won't set up)
2 whole eggs
2 egg yolks
1 tsp. vanilla
1/4 c. sugar
1 c. heavy cream
Melt together the semi-sweet chocolate pieces and the Kahlua over very low heat and set aside. (I use the microwave.) In blender, blend whole eggs, egg yolks, vanilla, and sugar. Blend for 2 minutes; add heavy cream and blend for 1 minute longer. Add chocolate and Kahlua mixture and blend until smooth. Chill about 3 hours. Makes about 5 champagne glasses. Serve with whipped cream. (I make ahead 1 day and put in Keebler chocolate pie crust. It's yummy!)