For Bolognese lasagna, we need ragù, lasagna, and béchamel. First, we'll prepare the Bolognese ragù. Bolognese ragù: 1. In olive oil, sauté onion, add diced carrot, celeriac, and after a moment, pancetta. 2. Then add ground meat (950 g of beef and 250 g of pork), season with salt and pepper, and sauté. 3. Pour in wine and let it evaporate. Then stir in tomato paste, sauté, add tomatoes, water, cover, and let it simmer gently. After an hour, add more water and stew for another hour (30 minutes covered, 30 minutes uncovered). Then add milk and simmer for 10 minutes. Béchamel: 1. In butter, sauté flour, gradually pour in milk, season with salt, and taste with nutmeg. Layering: In the dish, spread a layer of ragù. On the ragù, arrange lasagna, spread with béchamel, add another layer of ragù, sprinkle with parmesan, and again layer lasagna, béchamel, ragù, parmesan - repeat several times until the ingredients are used up. The last layer is béchamel, ragù, and on top parmesan.