Prepare the white sauce. Peel and cut into small pieces the celery, carrot and half onion. Put in a pan a tablespoon of oil and when it is hot, add the vegetables cut into small pieces, blend with white wine little by little. Spend two minutes on high heat and add the minced lamb, mix well with a wooden spoon until the meat has lost its red color. Combine milk, water q.b. to cover everything, the bay leaf, sage leaves, salt, pepper and some coriander grain. Lower the flame and cook for about half an hour (more or less the water should be absorbed, otherwise let it go a little further). Prepare the bechamelle. Heat the 250g of milk, melt the butter over a very sweet flame, add the flour in a single stroke and mix with a whisk; add milk and salt very little. Continue to mix until it has thickened but taking care to keep it a little fluid. Prepare the catalogna.Browse the catalog and use only the outer leaves (with the internal sprouts we will make a beautiful salad of puntarelle), wash them carefully; in a pan fry the garlic and a teaspoon of anchovy paste in a tablespoon of oil, when it begins to make the bubbles remove the garlic and add the leaves of Catalonia, make them flavor, add two tablespoons of water and cover. Cook frequently turning about a quarter of an hour (even here the water must be absorbed) and switch off. Turn on the oven at 180 °. Cut the mozzarella into chunks and lose the water. Prepare the filling of the pumpkin flowers. Clean the pumpkin flowers, without washing them, with moistened kitchen paper and remove the pistil and the side sepals with tweezers. In a small mixer crumble the breadcrumbs, with the other teaspoon of anchovy paste, the capers, the ricotta and a tablespoon of oil. Season with salt if necessary. Open the flowers very gently so as not to break them, insert a small piece of mozzarella (not all) and a generous teaspoon (also depends on how large the pumpkin flowers) of stuffing. Close them gently and place them in a greased pan. Sprinkle with very little oil and cook in the oven for about a quarter of an hour. In the meantime, place a large pot of salted water on the fire and when it is boiling, toss the conchiglioni and cook for two minutes less than the time indicated on the package. Then drain them and put them on a very clean cloth to prevent them from sticking. Grease a large pan. Add half of the bechamelle and half of the pieces of mozzarella remaining in the white sauce (now cold) and mix well. With a teaspoon, gently place the filling with the white ragù in the conchiglioni and arrange them aligned well, but so that they do not touch, in a beautiful large baking dish (to make them stay wider you can also use two pans). Season with the bechamelle and the remaining mozzarella chunks. Bake for twenty minutes. Impact. Helping with a fork to form two nests with the leaves of Catalonia, lean on the same number of conchiglioni and two side flowers of pumpkin.