Prepare the pasta: Bring a large pot of salted water to a rolling boil. Add the pappardelle pasta and cook for 7-9 minutes until al dente. Reserve ½ cup of the cooking water, then drain and set aside.

Sear the steaks: Heat 1 tablespoon of olive oil in a skillet over medium-high heat. Season the steaks with salt and pepper and sear for 3-4 minutes on each side until browned. Remove and let rest.

Sauté onions, garlic, and mushrooms: Lower the heat and add remaining olive oil to the skillet. Sauté chopped onions for 3-4 minutes until translucent. Add minced garlic and cook for 1 minute, then stir in sliced mushrooms and thyme and sauté until mushrooms are golden brown.

Make the creamy sauce: Pour in the beef broth to deglaze the skillet, scrape any browned bits. Simmer for 2-3 minutes. Stir in heavy cream and simmer for 3-4 minutes until thickened.

Combine and serve: Add sliced steak and pappardelle to the creamy sauce, toss to coat. Adjust consistency with reserved pasta water if too thick. Garnish with fresh parsley before serving.