Prepare Besciamella Sauce: In a saucepan, heat 4 cups of whole milk over medium heat until it simmers but does not boil. Meanwhile, in a separate pan, melt 4 tablespoons of unsalted butter, whisk in 4 tablespoons of all-purpose flour, and cook for about 3 minutes until golden. Gradually whisk in the warm milk until smooth and thickened. Stir in 1 cup of grated Parmesan, a pinch of grated nutmeg, salt, and pepper. Cover to prevent a skin while you prepare the Bolognese sauce.

Make Bolognese Sauce: If you haven't done so already, prepare your Bolognese sauce on the stove. Use a large skillet over medium heat and cook until the sauce is simmering and fragrant, about 15-20 minutes. Stir occasionally, ensuring the sauce thickens and develops its rich flavors. Once ready, set aside to cool slightly while you cook the lasagna noodles.

Cook Lasagna Noodles: In a large pot, bring a salted gallon of water to a rolling boil. Add the dried lasagna noodles and cook for just ¾ of the time indicated on the package, which usually takes around 8-10 minutes. Drain the noodles carefully in a colander, then lay them out flat on clean kitchen towels to prevent sticking while you assemble the lasagna.

Assemble Lasagna: Preheat your oven to 400°F. In a buttered baking dish, start with a layer of Bolognese sauce to prevent sticking. Place a layer of cooked noodles over the sauce, then pour a generous amount of the besciamella on top, followed by a sprinkle of grated Parmesan. Repeat the layers, finishing with a top layer of noodles, the remaining Bolognese, besciamella, and a final sprinkle of Parmesan to create a golden crust.

Bake: Once assembled, place the lasagna in the preheated oven and bake for 20-25 minutes, or until the top is bubbling and golden brown. Keep an eye on it towards the end of the cooking time. Remove from the oven and allow it to cool for about 10 minutes before slicing into the lasagna.