Make the ragù: Heat olive oil, sauté onion, carrot, celery. Add ground meat, brown well. Deglaze with wine. Stir in tomato paste, passata, broth. Season and simmer 1–1h 15 min.
Make the béchamel: Melt butter, whisk in flour. Slowly add milk while whisking. Season and cook until thick and creamy.
Assemble the lasagna: In a baking dish, spread ragù. Layer pasta → ragù → béchamel → parmesan. Repeat, finishing with béchamel + parmesan.
Bake: Cover with foil, bake 25 min at 180°C (350°F). Remove foil, bake 20 min more until golden.
Serve: Rest 10 minutes before slicing.