In a heavy pot over medium heat, melt 2 tablespoons of unsalted butter and 2 tablespoons of olive oil. Add 4 ounces of diced pancetta and cook until crispy for about 5 minutes. Remove it and set aside. Sauté a finely chopped onion, 1 carrot, and 1 celery stalk for 5 minutes. Introduce 1 pound each of ground beef and pork, cooking slowly for 10-15 minutes until no pink remains. Stir in 2 tablespoons of tomato paste, then deglaze with 1 cup of red wine. Add 28 ounces of canned crushed tomatoes, ½ cup of milk, and bay leaves. Simmer uncovered on low heat for 2.5 to 3 hours, stirring occasionally.

Bring a large pot of salted water to a boil. Add the lasagna noodles and cook until al dente, about 5-7 minutes. Drain the noodles and lay them flat on parchment paper drizzled with olive oil to prevent sticking. Set aside.

In a saucepan, melt 4 tablespoons of unsalted butter. Whisk in ¼ cup of all-purpose flour, stirring for 2 minutes until it forms a light roux. Gradually pour in 3 cups of warmed whole milk while whisking to avoid lumps. Continue whisking as it thickens, about 8-10 minutes, until thick enough to coat the back of a spoon. Season with a pinch of nutmeg and salt. Remove from heat.

Preheat your oven to 375°F (190°C). Grease a 9x13 baking dish and spread a thin layer of béchamel on the bottom. Place 2-3 noodles over the béchamel, followed by a generous layer of Bolognese sauce, then another layer of béchamel, and a sprinkle of grated Parmesan. Repeat the layering until all ingredients are used, finishing with a final layer of béchamel and topping with sliced fresh mozzarella and additional Parmesan.

Cover the assembled Lasagna with aluminum foil and bake for 1 hour. Remove the foil and bake for an additional 15 minutes, or until the top is golden and bubbling. Let it rest for 20-30 minutes before slicing.

Once rested, slice the lasagna into squares and serve hot with a generous sprinkle of freshly grated Parmesan. Pair with a fresh salad or crusty bread.