Flourless Chocolate Cake:
10 ounces bittersweet chocolate
1/3 cup water
5 large eggs
½ granulated sugar
¼ teaspoon salt
2/3 cup heavy cream
3 ounces bittersweet chocolate, coarsely chopped
1/3 cup heavy cream
½ teaspoon vanilla extract
Milk Chocolate Drizzle:
2 ounces milk chocolate, chopped
Make the cake:
1. Position a rack in the center of the oven and preheat the oven to 350F. Place a 9-inch cake pan on a piece of parchment paper and trace around it with a pencil. Cut out the round from the parchment paper. Grease the bottom and sides of the pan. Line the bottom of the pan with the parchment round, with the pencil lines against the pan. Grease the paper and set the pan aside.
2. Put the chocolate and water in a medium-size stainless steel bowl and place the bowl over a pot of barely simmering water. Heat, stirring frequently, until the chocolate is completely melted and the mixture is smooth. Remove the bowl from over the pot and set the chocolate aside to cool until tepid.
3. In the bowl of an electric mixer, whisk together the eggs, sugar, and salt by hand. Set the bowl over a saucepan of simmering water, making sure that the bottom of the bowl does not touch the water. Heat the egg mixture, whisking constantly, until the eggs are warm. Transfer the bowl to the electric mixer stand and, using the whisk attachment, beat on high speed until the mixture has tripled in volume, about 3 minutes.
4. In the bowl of an electric mixer (or with a hand-held mixer or by hand), beat the heavy cream until firm peaks just begin to form.
5. Using a rubber spatula, gently fold the cooled chocolate into the egg mixture. Fold in the whipped cream.
6. Scrape the batter into the prepared pan and place the pan into a roasting pan. Place the roasting pan in the oven and pour enough very hot water into the pan so that it comes halfway up the sides of the cake pan. Bake the cake for 45 to 52 minutes, until a toothpick inserted into the center of the cake comes out clean. Remove the pan from the water bath and place it on a wire rack; let the cake cool in the pan for 25 minutes.
7. Run a paring knife around the edge of the pan to loosen the cake. Carefully invert the cake onto wire rack. Cool completely.
8. Refrigerate the cake for 2 hours (if your wire rack doesn’t fit in the refrigerator, very carefully —the cake is quite delicate at this point — slide the cake onto a cardboard cake round).
Make the glaze and glaze the cake:
9. Place the chocolate in the bowl of a food processor and process just until finely ground.
10. Place the cream in a small saucepan and bring to a boil. Remove from heat and add the chocolate to the pan. Stir until the chocolate is completely melted and the mixture is smooth. Stir in the vanilla extract. Transfer the glaze to a small bowl. Cover the surface of the glaze with a piece of plastic wrap and let it cool for about 10 minutes before using.
11. Place the cake (either on a cake round or not) on a wire rack over a waxed paper or parchment paper lined baking sheet (to catch the drips). Pour the glaze on top of the cake spread it evenly over the top and sides, covering it completely. Refrigerate the cake for at least 30 minutes before drizzling it with the milk chocolate.
Finish the cake:
12. Put the chocolate in a medium-size stainless steel bowl and place the bowl over a pot of barely simmering water. Heat, stirring frequently, until the chocolate is completely melted.
13. Pour the melted chocolate into a small parchment paper cone or small sealable plastic bag (seal the bag and snip a tiny hole in one of the bottom corners). Remove the cake from the refrigerator and drizzle the chocolate in a diagonal zigzag pattern over the top. Refrigerate the cake for at least 20 minutes to set the chocolate.
Leave the cake at room temperature for 30 minutes before serving.