Prepare ingredients per instructions above.
Season the beef with salt and pepper.
Heat a large skillet over medium heat and cook the bacon until crisp (about 5 minutes). Remove the bacon and set aside. Drain excess fat, leaving 1/2 TBSP in the pan per serving.
Sear the beef on both sides until browned (about 2-3 minutes per side). Transfer to the slow cooker along with the bacon.
Add red wine, beef broth, crushed tomatoes, tomato paste, onion, garlic, celery, carrot, thyme, sage, red pepper flakes, butter, salt, and pepper to the slow cooker. Stir to combine.
Cover and cook on low for 6-8 hours, until the beef is tender and shreds easily (internal temperature should reach 190°F (88°C) for optimal tenderness).
Once cooked, remove the beef, let cool slightly, then shred. Discard the thyme sprigs.
Return the shredded beef to the sauce and stir in parmesan cheese. Keep warm on low.
Bring a large pot of salted water to a boil. Cook pappardelle/tagliatelle pasta according to package directions until al dente. Drain well. Toss in the ragu.