For the dish
Cook lasagna sheets according to the instructions on the packet, reducing cooking time by 2-3 minutes.
Cool in iced water, strain and dry.
Drizzle lightly with a little olive oil.
Place a pot over high heat, add the olive oil and ground beef, season with salt and sauté, stirring frequently until it turns golden brown.
Add the onion, carrot, peppers and prosciutto.
Season with salt and sweat until soft.
Add garlic and, as soon as it has released its aroma, add the tomatoes and stock.
Bring to the boil, reduce heat, season with salt again and add sugar if necessary. Simmer stirring occasionally until the liquid has absorbed, approx. 1 hour.
Add the thyme and tomato concasse and remove from the heat, allowing to cool slightly.
Add the graviera and stir well.
In a 24x30 cm. baking dish spread the tomato sauce and a layer or lasagna.
Continue with half the filling and repeat to form 3 layers of lasagna and 2 layers of filling.
Pour the béchamel over the layers and sprinkle with parmesan.
Bake in a pre-heated over at 170°C until the béchamel turns golden brown, approx. 15 minutes.