How to make
Beat the eggs and the sugar in a deep bowl with a mixer until doubled in volume, then add the milk, oil and lemon essence. Beat well until homogeneous.
Set aside 1 cup from this mixture (for the glaze). To the rest, add the flour and baking powder, stir and pour the cake mixture into an oiled and floured cake form (8″ (20 cm) in diameter) and bake the cake in a moderate 330°F (165 °C) oven until ready (about 30-40 min. depending on the oven).
While the cake is baking, make the glaze. Pour the set aside mixture into a pan or pot, crumble the chocolate into it and put it on a moderate stove.
Stir nonstop so that the chocolate melts and you get a light cream. Once the cream thickens a little, remove it from the heat (thickening takes just 5-10 min. after the mixture comes to a boil).
Leave the resulting cream/glaze to cool completely. Once the cake is baked, take it out of the oven and leave it to cool completely as well.
Once they're both cooled, cut the cake into slices, stir the glaze well and pour it on top of the cake. Form/distribute the glaze with a large knife or spatula, then sprinkle with the ground walnuts.