Crust
2/3 cup almond, finely chopped
1 1/4 cusp finely crushed vanilla wafers
1/3 cup butter, melted

Preheat the oven to 350 degrees F. Grease a 9-inch springform pan.

Place almonds on a baking sheet and toast in the oven for 3 to 4 minutes. Allow almonds to cool.

Place toasted almonds in a food processor, and process until finely ground. Combine wafer crumbs, ground almonds and butter. Mix well. Press the mixture onto the bottom of the springform pan and 1 1/2 inches up the sides. Bake 8 minutes. Place on a wire rack and let cool completely.

Filling
8 ounces (2 baking bars) bittersweet
    chocolate, broken into 1-inch pieces
8 ounces cream cheese, softened
1 cup granulated sugar
3 eggs
1 cup sour cream
1/4 cup almond-flavored liqueur
1/4 teaspoon salt (optional)

Melt chocolate in a double boiler over hot, but not boiling, water. Stir occasionally until the chocolate is smooth. Set aside. In a medium-size mixing bowl, beat cream cheese on low just until smooth. Gradually add sugar and continue beating until smooth. Scrape down the sides of the bowl and beaters with a rubber spatula. Add eggs, one at a time, beating well after each addition and scraping down the bowl as needed. With the mixer on low, gradually add sour cream, almond liqueur and salt, beating just until smooth.

Divide batter in half. Add melted chocolate to one half of the batter, stirring until smooth. Pour the chocolate batter into the crust; spread to create one even layer. Carefully spoon the plain batter on top of the chocolate batter. Place the pan in the oven and immediately reduce the temperature to 325 degrees F. Bake 50 to 60 minutes, or until the center is just set.

Turn off the oven, and leave the cake inside for 30 minutes with the oven door closed.

Transfer the cheesecake to a wire rack. Loosen it from the sides of the pan with a metal spatula. Let the cheesecake cool completely, then chill it at least 8 hours or overnight.

Store covered in the refrigerator.