Heat olive oil in a large pot over medium heat. Add chopped onion and minced garlic, and sauté until softened.
Add ground beef to the pot and cook until browned. Stir in tomato paste, crushed tomatoes, red wine, salt, pepper, oregano, and basil. Simmer for 45 minutes.
In a separate saucepan, melt butter over medium heat. Whisk in flour and cook for 1-2 minutes. Gradually add milk, whisking constantly until the sauce thickens. Season with nutmeg, salt, and pepper.
Preheat oven to 375°F (190°C). Spread a thin layer of Bolognese sauce in a baking dish. Layer with lasagna noodles, Bolognese sauce, béchamel sauce, and shredded mozzarella. Repeat layers, ending with béchamel sauce and a generous sprinkle of Parmesan cheese.
Bake in preheated oven for 45 minutes, until the top is golden and bubbly. Let it rest for 10 minutes before serving.