Begin by slicing two large onions and heating 2 tablespoons of butter in a large skillet over medium-low heat. Add the onions and cook slowly for 20-25 minutes, stirring frequently until they turn golden brown and are soft. Season with a pinch of salt and pepper, then remove from heat and let them cool while you prepare the meat mixture.

In a spacious mixing bowl, combine 1 pound of ground beef, half of the cooled caramelized onions, 1 teaspoon each of garlic powder and onion powder, 2 tablespoons of Worcestershire sauce, 1 large egg, and 1 cup of breadcrumbs. Mix gently using your hands or a fork until all ingredients are just combined.

Preheat your oven to 350°F (175°C). Transfer the meat mixture into a greased loaf pan, shaping it into a smooth loaf. Place the loaf pan in the oven and bake for 45-50 minutes, or until the internal temperature of the meatloaf reaches 160°F (71°C) and is firm to the touch.

After the initial baking time, carefully remove the meatloaf from the oven. Top with the remaining caramelized onions and a generous layer of Swiss cheese. Return the meatloaf to the oven for an additional 10-15 minutes, until the cheese has melted and is bubbly.

Once baked, remove the meatloaf from the oven and let it rest for about 5 minutes. Cut into thick slices and serve.