Heat half of the olive oil in a large frying pan over medium-high heat. Sear the lamb shanks for about 6-8 minutes until browned, then set aside.

In the same pan, add remaining olive oil, reduce heat to medium, and sauté the chopped onion for about 5 minutes until softened. Add bacon rashers and cook until browned, about 3-4 minutes.

Sprinkle plain flour over the onion and bacon mixture, stirring for 1 minute. Add tomato paste, minced garlic, and paprika; mix well for another minute.

Transfer the onion mixture to a slow cooker. Pour in chicken stock and stir. Add the assorted mushrooms and brown lamb shanks. Season with salt and pepper, cover, and cook on HIGH for 4 hours or LOW for 8 hours.

After cooking, remove lamb shanks and stir sour cream into the sauce until creamy. Adjust seasoning as needed.

Cook pappardelle according to package instructions. Serve lamb shanks over pasta, drizzling sauce on top, and garnish with parsley.