Heat olive oil in a large skillet over medium heat. Sauté onion, carrot, and celery until softened, about 5 minutes. Add garlic and cook for 1 minute.
Add ground beef to the skillet, cooking until browned. Season with salt, pepper, and Italian seasoning.
Stir in crushed tomatoes and beef broth. Reduce heat to low and simmer uncovered for 30-40 minutes, stirring occasionally.
Add milk to the sauce in the final 10 minutes of cooking to enhance richness.
Meanwhile, cook tagliatelle in salted boiling water until al dente. Drain and toss with the Bolognese sauce.
Serve hot, garnished with parsley or a sprinkle of Parmesan cheese.