Asparagus flan (flan di asparagi)

01114 ASPARAGUS FLAN with egg SAUCE code: 1114 INGREDIENTS for 4 people: 4 asparagus; 1 egg; half an onion; nut 1; 2 tablespoons milk; Salt; oil; Egg sauce: 1 dl of fresh cream; 1 egg yolk; 60 g grated Parmesan; some saffron stamens; salt and pepper. Remove the hard part of the asparagus and cook them in salted water, taking care that you don't break. Keep aside the cooking broth. In a little oil sauté the chopped onion, add the asparagus and half a cup of asparagus broth, Cook for a few minutes. Puree with the egg and milk, just enough to get a fine puree, season with salt and pour the mixture into a buttered flan mould. Cook in the oven in a water bath for 15 minutes. Turn the mold onto a plate and serve with hot sauce. Egg SAUCE: pour the milk into a saucepan, add the egg yolk and stir with a wooden spoon to mix the two ingredients well. Put on the fire, very low flame and cook stirring constantly until the mixture will tend to become a bit more dense. Withdrawn from heat and add cheese, stir well and add saffron.