5 large eggs
9 ounces bittersweet chocolate, coursely chopped
1 cup sugar
5 Tablespoons unsalted butter, cut into chunks
2 Tablespoons coffee or water
1/3 cup all purpose flour
pinch of salt
Center a rack in the oven and preheat the oven to 350 degrees F. Spray the bottom of a 9-inch spring form pan with cooking spray, line the bottom with parchment paper, and spray the paper and sides of the pan with butter/flour baking spray. Place the pan on a baking sheet covered with parchment or a silicone mat.
Separate the eggs, putting the whites in a mixer bowl and the yolks in a small bowl.
Set a heatproof howl over a saucepan of simmering water and add the chocolate, sugar, butter and coffee. Stir occasionally until the chocolate and butter are melted; the sugar may be grainy and that’s fine. Remove the bowl from the saucepan and set aside to sit for three minutes.
Using a rubber spatula, stir in the yolks one by one, then fold in the flour.
Working with the whisk attachment of the mixer or hand mixer, beat the egg whites with a pinch of salt until they hold firm but glossy peaks. Using the spatula, stir about one quarter of the beaten whites into the batter, 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 - 45 minutes, or until the cake has risen 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 cake to a cooling rack and let the cake rest for 5 to 10 minutes.
Carefully release the side of the pan and remove it, then turn the cake over onto a rack and remove the pan bottom and parchment paper. Invert the cake onto another rack and cool to room temperature, right side up. As the cake cools, it may sink.
For the Glaze
4 ounces bittersweet chocolate, coarsely chopped
1/2 cup heavy cream
2 teaspoons light corn syrup
First, turn the cooled cake over onto another rack so you’ll be grazing the flat bottom, and place the rack over a baking sheet lined with parchment 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 warm, but 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 tip 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 its charm. allow the glaze to set at room temperature or, if you’re impatient, slip the cake into the fridge for about 20 minutes. If the glaze dulls in the fridge, just give it a little gently heat from a hairdryer.