Hi
@Chook,
My -- you are planning early for Xmas. Thanks, by the way, for your question. It is always nice to have other "foodies" around to share.
My recipe is from a German site and I adjusted the recipe to work for low-carb. It is quite similar to the one you found (only traditionlly Austrians and Germans, would use any cream in high content chocolate and probably less sugar/sugar substitute as cakes here aren't as sweet as in many other countries. This is especially true for Sacher torte).
-- I started with the recipe for low-carb chocolate mousse (I posted the chocolate mousse recipe below this recipe) and just added about a quarter of cup of almond flour, which I sifted and folded under carefully (as not to lose any volume of the chocolate mousse).
-- I backed this mixture in the oven for about 45 minutes. It is ready when you can insert a tooth pick in the middle and it comes out clean.
-- Let it cool and than cut into two layers (even three if you like).
-- Heat jam or marmelade with a small amount of water. (I used low-carb blackberry-tonka bean marmelade with xylitol because this is what I had at home, but probably any marmelade/jam with enough flavor to not get overpowered by all that chocolate will work. The traditional recipe uses apricot).
-- Spread the jam/marmelade between each layer of cake. I also put the jam on top of the cake to make the flavor more intense.
-- Put a pot on the stove, melt some xylitol (or other sweetener), reduce the flame (I used 60 degrees centigrade), melt in high cocoa content chocolate).
-- Pour all the chocolate on top the cake and carefully spread it with a spatula, letting it run down the sides of the cake. If there are some parts without chocolate on the side of the cake, you can use the spatula to pull some of the chocolate, which has dripped onto the plate, up the sides again.
-- Refrigerate until the chocolate solidifies.
(Here is the recipe for the chocolate mousse)
-- Separate six eggs.
-- Add about half a cup of xylitol (or erythritol) to the egg yolks (or half to the egg whites and half to the egg yolkes -- doesn't really matter as long as you use some for the egg yolks).
-- Beat the egg whites first until stiff.
-- Beat the egg yolkes until the mixture becomes light yellow and approximately triples in volume.
-- Melt high cocoa content chocolate (maybe about 85% cocoa content) with butter (about 125g). Make sure to do this on a low flame, so that the chocolate doesn't burn.
-- Let the chocolate mixture cool a bit, so that it won't cook the egg mixture.
-- Carefully fold the chocolate mixture into the egg yolks, trying to keep as much volume as possible.
-- Carefully fold the egg yolk-chocolate mixture into the egg whites -- again trying to maintain as much volume as possible. It does take approximately 5-10 minutes to get them to blend well.
Edited for spelling.