Passover Flourless Chocolate Cake
12 tablespoons unsalted butter
8 ounces good-quality bittersweet chocolate, roughly chopped
4 ounces good quality semi-sweet chocolate, roughly chopped
6 eggs, divided
1 1/2 teaspoon vanilla paste (or vanilla extract)
1/4 cup unsweetened cocoa powder
1/2 teaspoon salt
1 cup sugar, divided
Preheat to 350 degrees F. Lightly grease and flour a 10-inch round springform cake pan.
In a medium saucepan add the butter and chocolate, place over low heat, cook, stirring occasionally until melted, Whisk until smooth. Remove from the heat and allow to cool.
Separate 4 of the 6 eggs, place the egg whites and yokes in a separate mixing bowls. In the bowl with the egg yolks, add the vanilla paste, cocoa powder, salt, remaining two whole eggs and half the sugar. Whisk to combine. Slowly add the chocolate-butter mixture and whisk to blend. Set aside.
Place the egg whites in the bowl of a KitchenAid, fitted with a whisk attachment. Beat the egg whites until frothy. With the mixer running, slowly add the remaining 1/2 cup of sugar until firm peaks have formed.
Using a rubber tip spatula, gently fold the egg whites into the chocolate mixture and mix until incorporated. Be careful not to over-mix. Pour the batter into the prepared baking pan. Smooth the top with the spatula.
Place in the oven and bake until the top is slightly cracked and the center is firm, about 30-35 minutes. Remove the cake from the oven and allow to cool completely before slicing.