For the Cake:
2 sticks butter, softened
1 box brown sugar
3 extra-large eggs
3 squares unsweetened chocolate, melted
2 teaspoons vanilla extract
1 teaspoon baking soda
½ teaspoon salt
2¼ cups sifted all-purpose flour
1 cup buttermilk
For the Filling:
6 ounces orange marmalade
1/8 cup Grand Marnier or orange liqueur
For the Frosting:
3½ tablespoons light Karo corn syrup
½ stick butter
2 tablespoons water
1 tablespoon Kahlua, brandy, orange liqueur or vanilla
1 cup semisweet chocolate chips
Cream together the butter and brown sugar. Mix in the eggs, then add the melted chocolate and vanilla and mix well. Preheat the oven to 350°F. In another bowl, mix the baking soda, salt and sifted flour. To the chocolate mixture, alternate adding the flour mixture and buttermilk, a little at a time. Pour the batter into 2 greased and floured (or nonstick) round cake pans and bake for 30-35 minutes, or until a toothpick inserted in to the middle of each cake comes out clean. Cool the cakes on a wire rack.
In a small saucepan, over boiling water, mix the filling ingredients and cool. Invert one cooled cake layer onto a cake plate, then spread on the cooled filling. Carefully top with the other layer. Cover with plastic wrap, then aluminum foil and refrigerate overnight. Bring the cake to room temperature before icing.
In a medium saucepan, mix the Karo corn syrup, butter, water, and Kahlua, brandy, orange liqueur, or vanilla and bring to a boil. Stir in the chocolate chips and mix until melted. Let frosting cool and stir until it is the consistency of whipping cream. Frost the top and sides of the cake.