4 ounces fine quality bittersweet chocolate, broken into small pieces
14 ½ ounces unsalted butter, at room temperature
1 cup all purpose flour
½ cup plus 1 ½ tablespoons (2 ounces) unsweetened cocoa
1 ½ cups sugar
5 large eggs
3 large eggs yolks
1 teaspoon sweetened condensed milk mixed with 9 tablespoons cold water
2 teaspoons vanilla extract
12 ounces fine quality bittersweet chocolate, broken into small pieces
1/2 cup heavy cream
1/2 teaspoon ground cinnamon
1. Preheat the oven to 325 degrees. Lightly butter a 9-inch round cake pan. Sprinkle the inside of the pan with flour to coat and rotate the pan to coat the sides and bottom evenly. Tap out any excess flour. Set aside.
2. To make the cake, melt the chocolate and 2 ½ ounces of butter in a double boiler over medium low heat. Set aside to cool. Sift flour and cocoa together and set aside.
3. Beat the remaining 12 ounces of butter and the sugar in an electric mixer on medium speed until creamy and light in color. Add the whole eggs one at a time. Next add the egg yolks and continue to beat for 1 minute. Scrape the sides of bowl. Mix again for 20 seconds.
4. Reduce the speed to low. Add the flour mixture alternating with the milk beating until incorporated after each addition. Add in the melted chocolate and beat until incorporated, about 30 seconds. Add the vanilla and mix until incorporated.
5. Spoon the batter into the prepared pan, smoothing out the top with the back of a spoon. Bake for 1 hour and 10 minutes, until the cake begins to come away from the sides of the pan, the cake springs back when you touch and toothpick inserted in the center of the cake come out clean.
6. Remove the pan from the oven. Cool the cake completely on a rack. Run a knife around the edges of the pan. Place a flat plate on the pan. Holding the plate and pan firmly, invert with one quick motion. Remove the pan and allow the cake to cool completely.
7. To make the glaze, melt the chocolate, cream and cinnamon in a double broiler over low heat. Stir until the chocolate is completely melted. Set aside to cool completely, 10 to 15 minutes.
8. Using a metal spatula spread the glaze evenly across the cake allowing it to drip down the sides. Serve at room temperature.