For the cake: In a food processor, thin the carrots and reserve it. Mix the egg yolks with the sugar, must be homogeneous. Add gradually the thin carrots and mix well. At the same time you mix, add the oil in wire. Incorporate the flour and the Backing Powder, combine gradually with the cake batter.
In a bowl, beat the egg whites until stiff. Carefully and gradually beat the eggs white with the cake batter. Add crushed nuts, at your choice. Pour the mixture in a rectangular baking pan and bake in the oven at 356ºF (180ºC), for 25-30 minutes.
For the cover: Melt the chocolate with the butter and the sour cream (I did with the microwave). For time to time, mix the chocolate.
When the cake is baked, cover it with the chocolate and add some crushed nuts on the top. It goes to the fridge until the chocolate solidifies. Cut into little squares.