Lasagne di salsiccia piccante e polenta (spicy sausage and polenta lasagne)

Method

1. Heat the oil in a large saucepan over a low heat. Add the onion, celery and carrot, then cook until lightly coloured (about 8 minutes). Split open the sausages and crumble the meat into the pan (discard the skins), breaking up any large clumps with a spoon. Add the garlic, chilli and tomatoes, then bring to a simmer. Cook for 40 minutes.
2. Meanwhile, pour the vegetable stock into a separate saucepan
   and bring to the boil. Gradually whisk in the polenta, then reduce the heat and simmer for about 20 minutes, stirring frequently. Season to taste, then set aside to cool a little.
3. Heat the oven to 160°C fan/gas 4. When the sauce has finished cooking, remove it from the heat and stir in the parsley. Lightly oil the baking dish, then spoon in a third of the sausage sauce. Spread a third of the polenta over the top, then sprinkle over a third of the pecorino and lay a third of the mozzarella slices on top. Repeat these layers twice more, finishing with a layer of polenta and the cheeses.
4. Bake for 40 minutes until bubbly and golden. Leave to stand for 5-10 minutes, then serve with crusty bread.