Description

You will need a 10" springform pan for this recipe. The cake also bakes in a water bath, so when you start the recipe, be sure to also start heating a kettle of water. Note: The cake needs to cool completely before topping with the ganache, and then chill a good two hours before enjoying. This is a very dense, very rich cake. Small slices served with lightly-sweetened whipped cream will be very satisfying.

Ingredients

Scale

For the Cake:

1 cup water
3/4 cup sugar
9 TB unsalted butter
1/2 tsp fine-grain salt (like table or sea salt)
18 oz bittersweet chocolate (~60%), chopped
6 large eggs, room temperature

For the Ganache:

1 cup heavy cream
1/4 tsp fine-grain salt (like table or sea salt)
8 oz semisweet chocolate (~50%), chopped

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Instructions

For the Cake:

Preheat oven to 350 degrees.
Butter the bottom and sides of a 10" springform pan and line the bottom with parchment. Then prepare the pan for the water bath: Wrap in two layers of plastic wrap and two layers of heavy-duty aluminum foil. Set aside.
In a small saucepan, combine the water and sugar. Bring just to a boil over medium heat, stirring, until the sugar is completely dissolved. Remove from heat and set aside.
In a large saucepan, melt the butter with the salt. Over low heat, add the chocolate and stir until smooth. Whisk in the sugar syrup, then let the chocolate mixture cool for ~5 minutes (this helps prevent the eggs from scrambling when added in the next step).
Whisk in the eggs, one at a time, until fully incorporated. The batter should look shiny and be slightly viscous. Pour into the prepared pan.
Bake in a water bath until the center is just set, about 30 minutes (see note). Remove the pan from the water bath, take off the foil and plastic wrap, then let cake cool completely - while still in the pan - on a wire rack.

For the Ganache:

In a small saucepan over medium heat, bring the cream and salt to a simmer. Off heat, add the chocolate and whisk until smooth.
Pour ganache over the cooled cake - still in its pan. Gently shake to evenly distribute the ganache.
Refrigerate cake in pan until the ganache is set, about 2 hours.

The cake is best served at room temperature. If your house is as cold as ours, zapping a piece in the microwave for ~10 seconds (keep an eye on it so it doesn't melt!) is magical.

Notes

As this cake is basically all chocolate, it should be obvious you'll want to use your absolute favorite. I like to mix up the complexity and depth of flavors by using two different types of chocolate. To note, if you prefer using darker chocolate (e.g. 70% or higher), the higher cocoa content will make the cake slightly drier.
To be extra fancy, you can first strain both the cake batter and the ganache through a chinois or fine-mesh strainer to knock out any air bubbles, producing a smoother finish.
To create a water bath, place the wrapped pan in a larger roasting pan and fill with hot(!) water halfway up the sides. It helps to add the water when the pan is already in the oven - less sloshing around!
The original recipe states to bake the cake for 50 minutes. I've never had to bake it anywhere near that long! And I've been making this recipe for years, in all types of ovens. The main thing to watch for is to bake the cake until the center is just set. Longer, and the cake will be much denser than a cake made from 1.5 pounds of chocolate already is! 😉
Pro Tip: To slice the cake with clean edges, run a sharp knife under hot water to heat the blade. Quickly dry it off, and then slice. Repeat for each cut.
Recipe adapted from the cover feature of the September 2006 issue of Bon Appetit magazine, courtesy of chef Jason Aronen of the now-shuttered Wilde Roast Cafe in Minneapolis.