Preheat oven to 300°F.
Pat the short ribs dry, season with salt and pepper, and sear in a Dutch oven with olive oil on all sides. Set aside.
In the same pot, sauté the carrots and onions until soft, about 10 minutes. Add garlic and cook for 2 more minutes, then add tomato paste and cook for 3 minutes.
Pour in the wine, scraping the bottom of the pot to loosen any stuck-on bits. Add tomatoes, thyme, and bay leaf, and bring to a simmer.
Return short ribs to the pot, cover, and cook in the oven for 2 hours. Then, cook uncovered for 1 more hour.
Remove ribs, shred the meat, discard bones and fat, and return meat to the pot. Season with salt and pepper.
Cook pappardelle according to package directions (1 minute less for al dente). Reserve 1 cup pasta water.
Mix pasta with ragu in a pan over medium-low heat, adding pasta water as needed.
Serve with grated Parmigiano Reggiano and extra ragu on the side. Enjoy!