Heat 1/2 cup cream in a heavy, non-reactive saucepot over moderate heat until cream comes to a low boil. Remove from the heat and add chocolate. Let the chocolate stand in hot cream 3-5 minutes to soften, then whisk together. Stir in Grand Marnier and chopped nuts, if using. Transfer to a fondue pot or set the mixing bowl on a rack above a small lit candle.
If fondue becomes too thick, stir in reserved cream, 1 tablespoon at a time, to achieve desired consistency. Serve with the pound cake, pretzels, shortbread cookies, pineapple and strawberries.