Melt the lard in a large, deep-sided saucepan set over a medium heat. When hot, add the pancetta and allow the fat to render

Next, add the chopped celery, carrot and onion and fry gently until softened, about 10 minutes

Add the pork and beef. Season well and brown the meat for about 10 minutes, stirring often. Once browned, pour over the wine and allow it to evaporate, using a wooden spoon to scrape any meat from the bottom of the saucepan

Finally, add the tomato sauce and stock, cover and cook over a very low heat for at least 2 hours. (Add a little bit of stock or wine if you see the ragù drying out.)

Half an hour before removing the ragù from the stove, add the sweetbreads, chicken livers and hearts. Finish cooking the ragù, uncovered, stirring occasionally

Now make the béchamel. Place the butter in a medium, deep-sided saucepan set over a medium heat. When melted, add the flour and whisk to combine into a paste (roux). Pour the milk over the roux in a thin stream, whisking all the while. Carry on cooking and whisking the béchamel until dense and perlaceous. Grate some fresh nutmeg on top, whisk once again, then remove from the heat and set aside

Preheat the oven to 180°C/gas mark 4

Grease a rectangular lasagne dish with butter and spread a ladleful of béchamel on the base of the pan. Cover with a layer of pasta sheets, followed by a layer of ragù, béchamel and grated cheese. Carry on in layers until you have reached the brim of the dish – there should be three layers at least – finishing with meat, béchamel and cheese

Bake for 30 minutes, or until deeply golden and crisp on top