Prepare the besciamella: Melt 30 g of butter with 200 ml of milk and 20 g of flour, mix and add a pinch of salt and pepper. At this point add also the gorgonzola (previously cut into pieces) and keep stirring the besciamella until it becomes a uniform and smooth mixture.
When the besciamella is uniform, add one yolk at the time as well as the beaten egg whites and a pinch of salt. Now pour the mixture in the 4 soufflé moulds (previously buttered and floured). Bake at 200° for 15 minutes.
In the meantime prepare the leek cream that will accompany the soufflé: thinly cut the leek and simmer it in a pan with a dash of olive oil. Add the remaining milk and keep cooking until the leek becomes soft. Afterwards, blend the mixture at medium speed and filter it. Adjust with salt and pepper and finally add the minced walnuts. When the soufflè is ready, serve it with the leek cream.
When you add the egg whites to the besciamella, delicately move your spatula from the bottom to the top, otherwise the whites will dismantle. Also, assure that there are no traces of yolk or you will have difficulties in beating the eggs.