Preheat your oven to 350°F (175°C).
Cook the bacon until crispy, then chop into small pieces.
Sauté the onions and mushrooms in the rendered bacon fat for about 5 minutes.
In a large bowl, combine ground beef, cooked bacon, sautéed mushrooms and onions, breadcrumbs, eggs, Worcestershire sauce, salt, pepper, and thyme.
Transfer the meat mixture to a loaf pan and shape it into a loaf.
Create a well in the center of the loaf and fill it with shredded Swiss cheese.
Cover the cheese with the remaining meat mixture, sealing it well.
Bake in the preheated oven for 60-75 minutes, or until cooked through.
Let the meatloaf rest for 10-15 minutes before slicing.
Slice and serve with your favorite sides.