Line an 8-in. square baking dish with parchment paper and coat with cooking spray.

Cream together softened butter and sugar until light and fluffy.

Add eggs one at a time, beating well after each addition.

Stir in vanilla extract.

In a separate bowl, combine chocolate syrup, water, orange liqueur, and orange zest.

In another bowl, whisk together flour, cocoa, baking soda, and salt.

Add the dry ingredients to the creamed mixture alternately with the chocolate syrup mixture, beginning and ending with dry ingredients.

Pour the batter into the prepared baking dish.

Bake at 350°F (175°C) for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Cool in the pan for 10 minutes, then invert onto a wire rack to cool completely.

Split the cake horizontally into two layers.

Sprinkle the cut sides of each layer with orange liqueur.

Place the bottom layer, cut side up, on a serving plate.

Spread the bottom layer with orange marmalade.

Top with the remaining cake layer, cut side down.

For the frosting, combine heavy whipping cream and light corn syrup in a heavy saucepan.

Bring to a boil, stirring constantly.

Remove from heat and stir in semisweet chocolate chips until melted and smooth.

Cool the frosting to room temperature, then stir until smooth.

Spread the frosting evenly over the top of the cake.

Garnish with kumquats, if desired.