Heat the olive oil in a large pot over medium heat. Add the onion and garlic, season with salt and black pepper, and cook for 3-4 minutes, stirring occasionally, until the onion is soft and translucent.
Add the mushrooms and ground beef. Cook for 5-6 minutes, breaking up the beef as it cooks, until browned and the mushrooms have released their liquid.
Stir in the tomato paste, then add the bay leaf, oregano, and thyme. Season with additional salt and black pepper to taste.
Pour in the red wine and stir, scraping up any browned bits from the bottom of the pot. Cook for 5-6 minutes, until most of the wine has evaporated.
Add the crushed tomatoes and reduce the heat to medium-low.
Simmer gently for 25-30 minutes, until the Bolognese has thickened.
If serving with pappardelle, bring a large pot of salted water to a boil and cook the pasta according to the package directions. Drain well.
Toss the hot pappardelle with melted butter to taste. Add the Gruyère, Parmesan, and chopped parsley and toss to combine.
Remove the bay leaf. Spoon the Beef and Mushroom Bolognese over the buttered pappardelle and garnish with additional cheese and fresh parsley. Serve and enjoy!