Preheat the oven to 325 degrees. Butter a 9inch round cake pan. Coat the bottom and sides with the toasted almonds.

In a large bowl, beat the cream cheese with an electric mixer at low speed until soft and smooth, about 1 minute. Combine the flour and sugar in another bowl and then add to the beaten cream cheese. Mix well, scraping down the sides of the bowl occasionally. Beat in the grated citrus zests. Add the eggs, egg yolks and vanilla extract. Mix thoroughly, frequently scraping down the sides of the bowl, until the batter is perfectly smooth.

Pour the batter into the prepared pan, tapping the bottom on a counter four or five times to eliminate air pockets. Place the cake pan inside a large roasting pan and pour in hot tap water until it reaches halfway up the sides of the cake pan. Bake 1 hour, or until the center feels firm when pressed. Immediately remove the cake pan from the larger pan and set aside to cool on a rack. Refrigerate 4 to 6 hours or overnight.

To serve, place the pan over a low burner for about 1 minute to melt the butter. Invert onto a plate and then invert again onto a serving platter so the nuts are on the bottom. To garnish, if desired, spread the sour cream evenly over the top and then cover the top with rows of thinly sliced kumquats.

Note: To toast almonds, preheat the oven to 350 degrees. Spread the almonds on a cookie sheet and toast in the oven until golden, about 15 minutes. Set aside to cool.