Cheesecake with Chocolate Streusel
Crust and Streusel
2/3 cup sugar
10 Tablespoons softened butter
2 1/2 cups all purpose flour
1/2 cup unsweetened cocoa powder
1 large egg
3 eggs, separated
1/2 cup plus 2 tablespoons sugar, divided
1/8 teaspoon salt
1/3 cup cornstarch
1/2 cup oil
lemon zest from 1 lemon
1 teaspoon vanilla extract
4 cups plain yogurt (or 2 cups quark)
* Quark is A soft, unripened cheese with the texture and flavor of sour cream.
If using yogurt and not quark, place a clean cloth in a colander which is placed over a large bowl, spoon the yogurt into it, fold the cloth over the top, add a small plate and a heavy can or glass of water on top for a weight. Let the whey drip into the bowl for about an hour or more. Then use in the filling.This is called yogurt cheese. If you have access to quark, use it straight from the package.
Preheat oven to 380°F.
Mix the first four ingredients for the crust until fine crumbs form. Add egg and mix again until the dough comes together in larger crumbs, like streusel. If still too dry, you may add a teaspoon or two of water.
Press 2/3 of the crust into a 10 inch buttered springform pan or two pie pans.
Reserve rest for streusel topping.
Beat the 3 egg whites until foamy. Drizzle in 1/2 cup sugar and 1/8 teaspoon salt and beat until soft peaks form. Do not overbeat. You should NOT be able to cut the egg whites with a knife.
In a separate bowl, beat the egg yolks with 2 tablespoons of sugar and the vanilla extract; add the yogurt cheese or quark and lemon zest and beat until smooth.
Sift the cornstarch over the filling mixture and mix well.
Fold in the egg whites.
Pour the filling mixture over the crust.
Top with the remaining streusel.
Bake for 30 minutes, then reduce the temperature to 350°F and bake for 15 minutes, or until set in the middle.
Refrigerate. The flavor is best when let to sit overnight.