Instructions for cake:
Preheat oven to 275 degrees. Grease and flour a 10-inch tube pan. Cream margarine, butter, and cream cheese, with sugar until fluffy and well combined. Add salt and vanilla, and mix well. Add eggs, one at a time, beating well after each addition. Add flour and mix well. Pour batter into pan. Place in a cold oven and bake at for 1 1/2 hours, or until done. Check doneness by inserting a toothpick in the center; if it comes out clean, it's ready. Cool in pan, then turn out and slice into half-inch-thick slices. Preheat grill pan to medium heat. Melt remaining 2 tablespoons butter and brush lightly on both sides of cake slices. Grill cake slices, turning once, until lightly grill-marked and slightly softened, about 2 minutes total.
Instructions for Bananas with Chocolate Sauce:
In a small saucepan, melt 2 tablespoons butter. Pour 1 cup heavy cream into another small saucepan and turn on the burner to medium-high. Scald the cream. Break up the semi-sweet chocolate bar into a medium mixing bowl. When the cream is hot, pour it over the chocolate and sets the bowl aside. In a large skillet, melt the other 2 tablespoons butter over medium-high heat. Peel 3 bananas, slice them and place in another mixing bowl. Add 1/2 cup sugar to the bananas, gently toss them and place them in the buttered skillet. When the bananas are golden-brown, add a dash of fortified wine and cook until it evaporates. Whisk the chocolate cream mixture until smooth, then add 2 tablespoons fortified wine, mixing well.
Put a cake slice on each dessert plate or parfait cup, top with a spoonful of the bananas, and then another cake slice and another spoonful of bananas. Drizzle the top of each dessert with the chocolate wine sauce.