Heat olive oil and butter in a large skillet. Cook the mushrooms for 6–8 minutes until browned. Add the onion and cook for 3–4 minutes, then stir in the ground veal and cook until browned. Add the garlic and cook for 30 seconds.
Sprinkle in the flour and cook for 1 minute. Season with salt, pepper, paprika, and herbes de Provence. Stir in the Worcestershire sauce and Dijon, then gradually add the beef broth.
Add the tagliatelle nests, pressing them into the broth. Cover and simmer for 10–12 minutes, stirring occasionally, until the pasta is tender.
Remove from the heat, let rest for 2 minutes, then stir in the sour cream until creamy. Finish with fresh parsley and serve.
