Preheat your oven to 350°F (175°C).

In a skillet over medium heat, cook the chopped bacon until crispy. Add in the finely chopped onions and mushrooms, sautéing until tender—about 5 minutes.

In a large mixing bowl, combine ground beef, sautéed bacon, onions, and mushrooms. Mix in breadcrumbs, eggs, and seasonings until well blended, being careful not to overmix.

Gently shape the meat mixture into a loaf shape and place in a greased baking dish.

Layer the Swiss cheese generously on top of the meatloaf.

Place the baking dish in the preheated oven and bake for about 1 hour, or until cooked through and juices run clear. Internal temperature should be 160°F (70°C).

Let the meatloaf rest for 10 minutes before slicing to ensure perfect slices.