Melt the chocolate and the margarine on a bain marie and transfer the mixture in an other large bowl.
Blend the sugar and the eggs untill they smooth.
Combine the sugar-eggs mix on chocolate-margarine and mix them untill they smooth.
After that add the flour and mix once again until you have a homogenized mixture.
Empty the mixture on a buttered and sugared baking pan (at this point you ca now add the chopped hazelnuts).
Baking time: approximately 25 mins in 185'C.
For the caramel sauce combine all the ingredients, except the milk and the vanilla extracts, on a pan and let them boil for 4-10 mins in medium temperature. After that add the milk and the vanilla extracts and mix.