This quadruple-layer cake isn't nearly as fussy to make as you might think. It starts out as a standard two-layer cake, then each layer is cut in half stacked, with an easy filling in between the layers. The result is a moist cake that keeps well without refrigeration; looks spectacular when cut, and tastes even better than it looks!

Follow our step-by-step photos for making this cake at our blog, Flourish. 
Want to make 2 dozen cupcakes instead of a layer cake? Enjoy our recipe for Favorite Fudge Birthday Cupcakes with 7-Minute Icing.
Cake
2 cups (14 ounces) sugar
2 cups (8 1/2 ounces) King Arthur  Unbleached All-Purpose Flour
2 tablespoons (3/8 ounce) Instant ClearJel® or cornstarch
3/4 cup (2 1/4 ounces) Double-Dutch Dark Cocoa or Dutch-process cocoa
2 teaspoons baking powder
2 teaspoons espresso powder
1/2 teaspoon baking soda
1 teaspoon salt
4 large eggs
3/4 cup (5 1/4 ounces) vegetable oil
2 teaspoons vanilla extract
1 1/4 cups (10 ounces) water

Filling
12 ounces semisweet chocolate
6 ounces cream (light, whipping, or heavy) or milk, or a combination*
flavors of your choice (see filling directions below)

*Hint: Since you need 4 ounces of cream for the icing, and you’ll most likely buy an 8-ounce container, use 4 ounces cream in the filling supplemented with 2 ounces of milk.

Icing
8 ounces semisweet chocolate
4 ounces cream (light, whipping, or heavy)
Preheat the oven to 350°F. Lightly grease and flour (or grease, then line with parchment, then grease again) two 8" x 2" round cake pans. Note: These pans need to be at least 2" tall; if you have non-standard, shorter 8" pans, substitute 9" round pans.

To make the cake: Whisk together the dry ingredients. Add the eggs, oil, and vanilla, beating until smooth. Gradually add the water, beating until smooth. Pour the batter into the prepared pans.

Bake the cakes for 35 to 38 minutes (a bit less if you use a 9" pan), or until a cake tester inserted into the center comes out clean. Cool the cakes in the pan for 15 minutes, then turn them out of the pans to cool completely on a rack.

To make the filling: Combine the chocolate and cream in a microwave-safe bowl, and heat until the cream is very hot, and the chocolate very soft. Stir to melt the chocolate completely, reheating very briefly if necessary.

Now you have a choice. You may either flavor the filling all one flavor, or use a different flavor for each layer of filling. For all one flavor, use 3 tablespoons of your favorite liqueur–Frangelico (hazelnut), Kahlua (coffee), or Framboise (raspberry) are all good choices. Or try 2 tablespoons rum. Alternatively, add 1 tablespoon espresso powder; or flavor to taste with a bottled extract (coconut, peppermint, cherry, almond…)

To mix and match flavors, divide the filling into three parts, and flavor each differently to taste, with an extract; or with about 1 tablespoon liqueur for each flavor. Divide the cooled layers in half horizontally, to make four layers. Place one layer on a serving plate, and spread with filling. Repeat with the next two layers. Top with the final cake layer.

To make the icing: Combine the chocolate and cream in a microwave-safe bowl, and heat until the cream is very hot, and the chocolate very soft. Stir to melt the chocolate completely, reheating very briefly if necessary. Pour and spread the icing over the top of the cake, letting it drip over the edges and down the sides. Once it’s done dripping, you may smooth the sides with an icing spatula, if desired. Allow the cake to rest, covered with a cake cover (or a big turned-over bowl) till the chocolate is set; overnight is good, though several hours are sufficient. Yield: 12 generous servings.