Set your oven to 375°F (190°C) for even baking.
Cook the bacon and veggies: Fry the bacon until crispy, then crumble it. In the same pan, sauté onions and mushrooms in the bacon drippings until soft, about 5-7 minutes. Let cool slightly.
Mix the meatloaf: In a large bowl, combine ground beef, ground pork, breadcrumbs, milk, Parmesan, sautéed onions and mushrooms, bacon, and Swiss cheese. Add eggs, Worcestershire sauce, ketchup, garlic powder, thyme, salt, and pepper. Mix gently until just combined.
Shape the loaf: Form the mixture into a loaf and place it in a baking dish or on a lined baking sheet. Spread ½ cup ketchup evenly on top.
Cook for 60-70 minutes, or until the internal temperature reaches 160°F (71°C).
Let the meatloaf sit for 10 minutes before slicing to keep it juicy and tender.