3 large eggs, separated (one yolk reserved for the frosting)
1/3 cup all-purpose flour
1/8 teaspoon salt
1/3 cup granulated sugar
1/2 teaspoon vanilla extract
1 batch Kossuth Cake Cream Filling (recipe follows)
1 batch warm Kossuth Cake Chocolate Frosting (recipe follows)

Kossuth Cake Cream Filling:
1 cup heavy whipping cream
1/4 cup granulated sugar
1/2 teaspoon vanilla extract

Kossuth Cake Chocolate Frosting:
2 1/2 ounces bittersweet chocolate
1/4 cup (1/2 stick) butter
2 1/3 cups confectioners’ sugar
3 tablespoons hot water, or more as needed
2 egg yolks, beaten (one leftover from the dough recipe)
1/2 teaspoon vanilla extract
1/8 teaspoon salt