In a saucepan over medium heat, heat the olive oil. Add the onion, carrots, and garlic, and saute until softened about 10 mins. Add the sage leaves and beef, breaking up the beef with a wooden spoon. Raise the heat to high and cook until meat is browned. Season with salt and pepper. Add the wine and cook until liquid has evaporated about 3 minutes. Stir in 1.5 C cold water and the bay leaf. Bring to a boil and stir occasionally. Reduce the heat to low, partially cover, and simmer for about 30 minutes. Season again with salt and pepper. Stir in the tomatoes and simmer on low for another 30 minutes. Meanwhile, in a large stock pot, boil salted water. Add the spaghetti and cook until tender about 9-10 minutes. Drain pasta and season ragu again if needed.Serve beef ragu over pasta and sprinkle with parmigiano cheese.