Because death by chocolate has several components I'm going to post a complete ingredients list a the top and then a separate list for each piece.

Combined Ingredients
2 pounds, 13 ounces semisweet chocolate
5 1/2 ounces unsweetened chocolate
4 3/4 cups heavy cream
3 1/4 cups granulated sugar
15 eggs
15 tablespoons plus 1 teaspoon unsalted butter
10 tablespoons cocoa
8 tablespoons plus 1 teaspoon all-purpose flour
1/2 cup water
5 tablespoons instant coffee
2 tablespoons sour cream
1 tablespoon corn starch
2 teaspoons pure vanilla extract
2 teaspoons dark rum
1/2 teaspoon baking powder
1/8 teaspoon cream of tarter

In reality, you could probably make this cake in one day, but it would be a lengthy undertaking. Split over three nights it's far more reasonable, and the various components keep just fine for a day or two.

Day 1: Chocolate Brownie
The recipe calls for using a springform pan. I didn't actually have one, which may have made things less visually pleasing, but a round cake pan still worked just as well. You do really need an electric mixer of some sort, it's a pretty good workout to whisk egg whites by hand until stiff.

Chocolate Brownie Ingredients
3 ounces semisweet chocolate, broken into 1/2 ounce pieces
4 tablespoons plus 1 teaspoon unsalted butter, softened
1 1/2 ounces unsweetened chocolate, broken into 1/2 ounce pieces
3 eggs
1/4 cup granulated sugar
1 teaspoon pure vanilla extract
8 tablespoons, plus 1 teaspoon all-purpose flour
1/2 teaspoon salt
1/2 teaspoon baking powder
2 tablespoons sour cream

Directions
1. Preheat the oven to 325 degrees.
2. Create a double boiler by heating some water over medium-high heat in a pot and placing a second pot on top so that it fits snugly and is not quite touching the water.
3. Place 3 ounces semisweet chocolate, 4 tablespoons butter, and 1 1/2 ounces unsweetened chocolate on the top part of the broiler. Cover it with film wrap and heat it for 6 to 7 minutes. Remove from the heat and stir until smooth.
4. Whisk the eggs, 1/4 cup sugar, 1 teaspoon vanilla in a bowl until it thickens. Coat a 9 x 1 1/2 inch cake pan with butter. Flour the pan with roughly 1 teaspoon and shake out the excess.
5. Combine the chocolate and egg mixtures.
6. Add 8 tablespoons flour, 1/2 teaspoon salt, and 1/2 teaspoon baking powder into the combined mixture.
7. In a separate bowl, whisk 2 tablespoons of sour cream and then combine it with the other mixture.
8. Pour the mixture into the cake pan and bake it for about 30 minutes or until a toothpick inserted in the middle comes out clean. Let the brownie cool for a bit before trying to remove it. If you are preparing this a day or two beforehand you can just let it sit and it comes out pretty easily.

Day 2: Meringue and Rum Sauce
This was actually the longest day of cooking because the meringue has to bake for several hours. Make sure you save yourself a lot of time this night.

Meringue Ingredients
4 egg whites
1/8 teaspoon cream of tartar
1/8 teaspoon salt
1 1/4 cups granulated sugar
2 tablespoons cocoa, sifted
1 tablespoon corn starch

Directions
1. Preheat the oven to 225 degrees
2. Whisk 4 eggs whites with an electric mixer on medium speed until frothy, about 1 minute. Add the cream of tartar and salt, increase mixer speed to high and whisk until the egg whites begin to stiffen, about 1 to 2 minutes. Gradually add a 1/2 cup sugar while continuing to mix. Pause and clean down the sides of the bowl.
3. Add the remaining 3/4 cup of sugar and keep whisking until soft peaks form, about 3 minutes.
4. Stop the mixer and add in the cocoa and cornstarch.
5. Take a 9-inch cake pan and trace it's outline on a sheet of parchment paper on a cookie sheet. This will serve as your guide for pouring the meringue. Turn over the sheet so the marked side is down and then weigh down the corners.
6. Pour the mixture into a pastry bag with a straight tip and fill in the circle starting at the middle and spiraling outward.
7. Place the meringue in the oven and bake for 15 minutes. Reduce the temperature to 200 degrees and bake for an additional 2 hours and 45 minutes. Take it out and let it cool before removing it from the sheet.

Chocolate Rum Sauce Ingredients
1/4 pound unsalted butter
1 cup granulated sugar
1 cup heavy cream
1/3 cup cocoa, sifted
2 teaspoons dark rum (we ended up using whiskey instead and it turned out fine)
1/8 teaspoon salt
1 tablespoon instant coffee
1 teaspoon pure vanilla extract

Directions
1. Heat butter in a saucepan over medium heat. When hot, add in the sugar, cream, cocoa, rum, and salt.
2. Bring to a boil and then let simmer for 5 minutes.
3. Remove from heat, add in coffee and vanilla extract.
4. Serve at room temperature.

Day 3: Ganache, two kinds of mousse, and assembly
Constructing the cake actually does take some time because you have to periodically refrigerate it to make the various layers hold together, so make sure you save yourself some time.

Chocolate Ganache Ingredients
22 ounces semisweet chocolate broken into 1/2 ounce pieces
1 1/2 cups heavy cream
3 tablespoons unsalted butter

Directions
1. Create another double boiler under medium-high heat.
2. Place chocolate, cream, and butter on the top half of the boiler and cover with plastic wrap. Heat for 3 minutes, remove the wrap, stir, and continue heating for 2 more minutes.
3. Remove from heat and stir until smooth.

Chocolate Mousse Ingredients
6 ounces semisweet chocolate, broken into 1/2 ounce pieces
1 1/2 cups heavy cream
3 egg whites
2 tablespoons granulated sugar

Directions
1. Prepare a double boiler over medium heat and place the chocolate in it. Cover with plastic wrap and let cook for 10 minutes. Remove from heat
2. Place cream in a bowl that has been cooled in a fridge or freezer. Whisk on high with an electric mixer for 1 1/2 minutes, wipe down sides of the bowl and then whisk again for 1 minute until peaks form.
3. In a separate bowl, whisk egg whites until peaks form. Add the sugar and whisk another 1 to 1 1/2 minutes until peaks form again.
4. Add one-quarter of the cream to the chocolate and combine. Then add in the egg whites and the rest of the cream and fold ingredients together.

Mocha Mousse Ingredients
14 ounces semisweet chocolate, broken into 1/2 ounce pieces
4 ounces unsweetened chocolate, broken into 1/2 ounce pieces
1/2 cup water
1/4 cup instant coffee
2 tablespoons cocoa, sifted
2 egg yolks
5 egg whites
2 tablespoons granulated sugar
3/4 cup heavy cream

Directions
1. Create a double boiler over medium high heat. Add both kinds of chocolate, water, coffee, and cocoa into the top half of the boiler. Cover with film wrap and heat for 5 to 7 minutes. Remove film wrap and stir until smooth.
2. Add egg yolks and continue to stir until smooth. Remove from heat.
3. Whisk 5 egg whites on high speed with an electric mixer until peaks form, about 2 to 3 minutes. Add in sugar and continue whisking until stiff, 2 minutes.
4. Whisk the heavy cream in a chilled bowl with an electric mixer until stiff. Fold a quarter of the egg whites into the chocolate mixture. Then add in the cream, followed by the rest of the egg whites.

Once all the components are made, it's time to construct death by chocolate. Here, a springform pan will help aesthetically because you can get the cake to fit into a perfect circle and then easily remove it.

Assembly Instructions
1. Cut the chocolate brownie in half horizontally and place one half in the bottom of a closed springform pan.
2. Ladle 1 1/2 cups of the ganache over the brownie.
3. Trim the meringue such that it fits perfectly over the brownie. Place it, top side up, on top of the brownie and press down gently to eliminate air pockets.
4. Spoon all of the mocha mousse over the meringue, spreading it evenly.
5. Place the other half of the chocolate brownie on top. Take the pan and place it in the freezer for 30 minutes or the fridge for 1 hour to help set the cake.
6. Remove the cake from the springform pan and pour the rest of the ganache over the cake, spreading evenly. Refrigerate for another 10 to 15 minutes.
7. Pour the chocolate mousse into a pastry bag with a star tip. Pipe a row of stars touching each other around the edge of the cake and then continue around the rest of the top until it is completely covered. Refrigerate again for at least 4 and preferably 12 hours before serving.

When serving the cake, pour some of the chocolate rum sauce on a plate, and then use a knife that has been run under hot water to cut slices. Place the piece of cake on top of the plate and enjoy.

Below are a series of pictures from making the cake.