Preheat the oven to 350°F (175°C).
In a skillet over medium heat, cook the chopped bacon until crispy. Remove and drain on paper towels, leaving 1 tablespoon of bacon fat in the pan.
In the same skillet, add the finely chopped mushrooms, onion, and garlic. Sauté until softened, about 5-7 minutes. Let cool slightly.
In a large mixing bowl, combine the ground beef, cooked bacon, sautéed mushroom mixture, shredded Swiss cheese, bread crumbs, milk, eggs, Worcestershire sauce, salt, pepper, and thyme. Mix until just combined; do not overmix.
Transfer the mixture into a meatloaf pan, pressing it down to shape it. Optionally, place the meatloaf on a baking sheet to catch any drippings.
Bake in the preheated oven for 60 minutes, or until the internal temperature reaches 160°F (70°C) as measured by a cooking thermometer.
Remove from the oven and let it rest for about 10 minutes before slicing. Garnish with fresh parsley if desired.
For added flavor, consider topping the meatloaf with a mixture of ketchup and brown sugar during the last 10 minutes of baking.