Hearty Beef Stew with Shells

Season beef generously with salt and pepper. In a large pot or Dutch oven, heat 2 tablespoons olive oil over medium-high heat. Add beef and cook, turning every 2 minutes, until browned, 6 minutes. Transfer to a bowl with any pan juices. Add remaining 2 tablespoons olive oil to pot, along with carrots, celery, onion, and garlic. Cook, stirring regularly, until softened, 5 minutes. Season with salt and pepper. Add beef and pan juices, wine, beef stock, tomatoes, bay leaves, rosemary, and thyme. Bring mixture to a boil, then reduce heat to low and let simmer 30 minutes. Meanwhile, bring a large pot of salted water to a boil. Boil shells until al dente, 8 minutes; drain. In a large skillet, heat butter over medium-high heat. Add mushrooms and cook until golden brown, 5 minutes. Season with salt and pepper. Remove thyme, rosemary, and bay leaves from the pot and stir in mushrooms and pasta shells. Season with salt and pepper and ladle into bowls. Garnish with parsley.