Brown celery and onion with 3 tablespoons of EVO oil. Add Prosciutto Toscano DOP, cut it into cubes and cook for 1 minute. To prepare béchamel sauce, melt 50 g of butter, join 50 g of flour, stir and dilute with half a litre of milk. Season with salt, pepper and a pinch of nutmeg. Cook and stir for 10 minutes. Grease an oven pan and put the lasagne sheets. Join béchamel, Prosciutto Toscano DOP and place Pecorino Toscano DOP grated and in pieces. Repeat the same operation for multiple layers. Put in the oven at 180 °C for half an hour. Allow to rest for a few minutes and serve.