Preheat the oven to 325 degrees. Butter a 9inch round cake pan and line the bottom and sides with almonds.
With an electric mixer at low speed, beat cream cheese until soft and smooth. With machine running, add sugar, cinnamon, lemon zest, and juice, beating well between additions. Add eggs, one at a time, beating well after each addition. Beat in vanilla. To ensure even mixing, be sure to scrape down the bowl between additions. Fold in the chopped chocolate evenly.
Pour batter into lined cake pan. Tap it 3 or 4 times on the counter to eliminate air pockets. Place inside a larger pan and pour in boiling water until it rises halfway up the sides of the cake pan. Bake about 45 minutes, until center feels firm when pressed.
Set aside to cool on a rack, then refrigerate 2 to 3 hours. To unmold, place pan over a low burner about 2 minutes. Invert onto a platter, then invert again (the nuts should be on the bottom). The cake can be kept in the refrigerator up to 2 days. At least two or up to eight hours before serving, top with the melted chocolate: Dip your fingers or a fork into the melted chocolate and drizzle over the center in a freeform pattern. Refrigerate until serving time.
c.1997, M.S. Milliken & S. Feniger, all rights reserved