This cake has long been a family favorite, both for its good taste and because it’s no-fail! Use a plain tube pan, not a pan with a non stick coating.
Preheat oven to 350 degrees Fahrenheit.
In the bowl of an electric mixer fitted with the whisk attachment, beat the egg whites until soft peaks form. Add the sugar in a thin slow stream and beat until stiff peaks form.
In a second bowl, beat the yolks and add the oil and the dissolved coffee. Mix all remaining ingredients together in a third bowl. Alternate adding the wet and dry mixtures into the whites, using the folding motion to incorporate.
Pour into a tube pan, or an unlined aluminum pan, and bake for 50–55 minutes. When done, turn upside down on the legs of the pan or the neck of a glass bottle to cool.
You can freeze in the pan, and then use a sharp knife to loosen the cake from the pan. If desired, spread chocolate cream (see below) while still frozen.
Place water and sugar in a double boiler and cook until sugar dissolves. Add the chocolate, cocoa powder, and vanilla sugar. Let the chocolate melt and mix well.
Add egg yolks, mixing constantly until they are incorporated. Finally, add margarine.
When the mixture is smooth, pour into a container and let it sit uncovered until it has completely cooled. Refrigerate or freeze until use.