Pappardelle, from an Italian verb meaning "to gobble up," is an apt name for a sturdy pasta that fills out a hearty veal stew.
Heat oven to 400 degrees. Trim silver skin from veal. Heat a Dutch oven coated with olive-oil cooking spray over medium heat until very hot. Add veal; cook until browned, turning as needed, about 5 minutes. Add onion, carrots, celery, and red pepper; stir to combine. Reduce heat to medium low, and cook until vegetables are softened, about 6 minutes. Increase heat to high, and add wine; cook until almost all the wine has evaporated, about 5 minutes.
Add chicken stock, mushrooms, and tomatoes; bring to a boil. Place cover on Dutch oven; transfer to oven. Cook 1 hour; remove lid, and continue cooking until veal is falling off the bone and sauce is quite thick, about 1 hour 10 minutes more. Using a wooden spoon, break the veal into smaller pieces, and remove the bones. Stir in crushed red-pepper flakes.
Bring a large stockpot of water to a boil while osso-buco sauce is finishing. Cook pappardelle until al dente, about 10 minutes. Drain in a colander, and transfer to bowls; top with sauce. Garnish with chopped rosemary, and serve.
The veal-stew sauce can be made a day ahead and reheated; the meat will be even more tender.