1. Preheat oven to 350 degrees. In a large Dutch oven or heavy pot with a lid, heat 2 tablespoons oil over medium-high. Add mushrooms and cook until browned, about 10 minutes. Transfer to a plate. Season beef generously with salt and pepper and add 1 tablespoon oil to pot. In batches, brown beef, 2 to 3 minutes per batch (adding up to 1 tablespoon oil per batch, if needed); transfer to plate. Pour off all but 1 tablespoon fat from pot. Add bacon and cook over medium until brown, 5 minutes. Add tomato paste; cook, stirring, 30 seconds. Add flour and cook, stirring, 30 seconds.

2. Return beef to pot; add wine, broth, bay leaf, and garlic. Bring to a boil, cover, and transfer pot to oven; cook 1 1/2 hours. Add carrots and onions and cook until meat is very tender, 1 to 1 1/2 hours more, adding mushrooms 15 minutes before end of cooking. Stir butter into stew and serve topped with parsley, if desired.