Preheat the oven to 375°F.
In a large skillet or Dutch oven, heat some olive oil over medium-high heat.
Add the ground beef and ground pork to the skillet and cook until browned, about 10 minutes.
Remove the meat from the skillet and set it aside.
Add the onion, celery, and carrots to the skillet and cook until softened, about 5-7 minutes.
Add the garlic to the skillet and cook for an additional minute.
Stir in the tomato paste and cook for another minute.
Add the red wine to the skillet and bring it to a simmer, scraping the bottom of the skillet to loosen any browned bits.
Add the crushed tomatoes, beef broth, bay leaves, salt, and black pepper to the skillet and bring the sauce to a boil.
Reduce the heat to low and add the browned meat back to the skillet. Cover the skillet and let the sauce simmer for 1-2 hours, stirring occasionally, until the sauce has thickened.
To make the béchamel sauce, melt the butter in a medium saucepan over medium heat.
Whisk in the flour and cook for 1-2 minutes, stirring constantly.
Gradually whisk in the milk and continue to whisk until the sauce has thickened, about 10 minutes.
Stir in the nutmeg, salt, and white pepper.
Cook the lasagna noodles according to package instructions until al dente. Drain the noodles and set them aside.
To assemble the lasagna, spread a layer of the Bolognese sauce on the bottom of a 9x13-inch baking dish.
Place a layer of lasagna noodles on top of the sauce.
Spread a layer of the béchamel sauce over the noodles, followed by a layer of shredded mozzarella cheese and grated Parmesan cheese.
Repeat the layers of Bolognese sauce, noodles, béchamel sauce, mozzarella cheese, and Parmesan cheese until you've used up all the ingredients.
Cover the lasagna with aluminum foil and bake in the preheated oven for 25 minutes.
Remove the foil and continue baking the lasagna for an additional 20-25 minutes, or until the cheese is melted and golden brown.
Let the lasagna cool for a few minutes before slicing and serving.
Garnish with chopped parsley, if desired.