Turn the oven up to 320°F (160 °C). Prepare a 10″ (26 cm) diameter cake form with a ring, covered with baking paper. Use a mixer only.
In the mixer bowl, put the egg whites (at room temperature), beat and add the sugar in lots. Don't beat to a thick snow because if you do your cake layers will end up too crumbly. Beat the whites until soften but not until runny either. They need to drip from the beaters slowly.
Once the sugar has melted completely (check with your fingers, if there's still sugar crystals beat again briefly) add the ground walnuts. Stir with a spatula. Weigh the dough on a scale, divide it up into 4-5 equal layers (usually 5) and pour them into the form, smooth them out.
Bake at 320°F (160 °C) about 5-7 min. Invert immediately and carefully remove the paper. At this point, the layers are still slightly sticky and soft but that's not an issue. Leave them aside to cool.
Melt the chocolate in a water bath. Take it off the stove and cool slightly for 5-7 min. Beat the cream with the mixer on low, add the sugar in lots. Pour in the melted chocolate in a trickle. Beat until homogeneous.
Stack the cake as follows: place 1 of the layers in a flat suitable cake plate, cover with 1/4 of the cream, cover with the next layer and continue until you've arranged them all. Cover with cream on all sides. Leave in the fridge for about 1 hour.
Melt the chocolate in a water bath, add the oil for a nice shine. Take it off the stove, pour a little of it in a small circle over the middle of the cake and tilt it sideways a bit to spread it out. Repeat with another serving of chocolate until you've used up all of it.
Don't use a spatula to spread it out. Leave in the fridge to harden. Always sprinkle with green-colored coconut flakes before serving, this is the trademark of the Chocolate Garash. Another option is to sprinkle with ground pistachios, baked in a pan briefly.
Cut it into narrow pieces with a sharp knife, dipped in hot water and dried ahead of time.
Source: Kosta Garash - 1885.
Notes: This is the original recipe for Garash cake, introduced by Hungarian confectioner Kosta Garash. It was first served in the town of Ruse and unveiled in Sofia in 1960. It consists of 5 egg white layers, smeared with chocolate mousse made of cream and chocolate.
It became emblematic for every self-respecting restaurant. It's always covered with green-colored coconut flakes. It also resembles the renowned Sacher cake.
Never use flour when making the layers.