This cake is almost like fudge -- rich and dense, with an impossibly chocolaty depth. The ingredient list is short and simple, and the only leavening used here is whipped egg whites. The glaze is supposedly optional, but the slight contrast between the cake and the glaze is what really "makes it" for me, so I would not recommend skipping it.
This cake is delicious on it's own, but to push it to truly decadent heights, try it with some raspberries and softly whipped cream, or just simply a small curl of good quality vanilla ice cream (I like Edy's "Dreamery" or Hagendas).
5 large eggs
9 oz bittersweet chocolate, coarsly chopped (I used dark chocolate with 50% cacao)
1 cup sugar
5 Tablespoons butter, cut into chunks
2 Tablespoons coffee or water (cold leftover coffee = OK)
1/3 cup all-purpose flour
For (optional) glaze:
4 ounces bittersweet chocolate, coarsly chopped
1/2 cup heavy cream
2 teaspoons light corn syrup
To make cake:
Center a rack in the oven and preheat the oven to 350 degrees F. Butter a 9-inch springform pan, line the bottom with parchment paper, butter the paper, dust the inside of the pan with flour and tap out the excess. Place the pan on a baking sheet lined with parchment paper or a silicone mat.
Separate the eggs, putting the whites in a mixer bowl or other large bowl and the yolks in a small bowl.
Set a heatproof bowl over a saucepan of simmering water and add the chocolate, sugar, butter and coffee. Stir occasionally until the chocolate and buter are melted; the sugar may still be grainy and that's OK. Transfer the bowl to the counter and let the mixgture sit for 3 minutes.
Using a rubber spatula, stir in the yolks one by one, then fold in the flour.
Working with a whisk attachment of the mixer or a hand mixer, beat the egg whites with the pinch of salt until they hold firm but glossy peaks. Using the spatula, stir about one quarter of the beaten whites into the batter to lighten it, then gently fold in the rest. Scrape the batter into the pan and jiggle the pan from side to side a couple of times to even the batter.
Bake for 35 to 45 minutes, or until the cake has risin evenly (it might rise around the edges and you'll think it's done, but give it a few minutes more, and the center will puff too) and the top has firmed (it will probably be cracked) and doesn't shimmy when tapped; a thin knife inserted into the center should come out just slightly streaked with chocolate. Transfer the pan to a cooling rack and let the cake rest for 5 to 10 minutes.
Run a blunt knife gently around the edges of the cake and remove the sides of the pan. Carefully turn the cake over onto a rack and remove the pan bottom and the parchment paper. Invert the cake onto another rack and cool to room temperature right side up. As the cake cools, it may sink.
To make optional glaze:
First, turn the cooled cake over onto another rack so you'll be glazing the flat bottom, and place the rack over a baking sheet lined with parchment or wax paper to catch any drips.
Put the chocolate in a small heatproof bowl.
Melt the chocolate over a pan of simmering water or in a microwave oven -- the chocolate should be just melted and only warm, not hot. Meanwhile, bring the cream to a boil in a small saucepan. Pour the hot cream over the chocolate and stir very gently with a rubber spatula until the mixture is smooth and shiny. Stir in the corn syrup.
Pour the glaze over the cake and smooth the top with a long metal icing spatula. Don't worry if the glaze drips unevenly down the sides of the cake -- it will just add to it's charms. Allow the glaze to set at room temperature or, if you're impatient, slip the cake into the refrigerator for about 20 minutes. If the glaze dulls in the fridge, just give it a little gentle heat from a hairdryer.
This recipe is from "Baking: From my home to yours" by Dori Greenspan.