01 -
Set the oven to 350°F (175°C) to warm up.
02 -
In a large skillet, melt butter over medium heat. Add sliced onions and sugar, then cook while stirring occasionally until golden brown and caramelized, about 20 minutes.
03 -
In a large bowl, combine ground beef, breadcrumbs, eggs, milk, Worcestershire sauce, salt, pepper, and dried thyme. Mix gently until just combined.
04 -
Fold the caramelized onions into the meat mixture, reserving a portion for topping.
05 -
Transfer the mixture into a loaf pan and press down evenly.
06 -
Spread the reserved caramelized onions over the top of the loaf and bake in the preheated oven for 45 minutes.
07 -
Remove the loaf, sprinkle shredded Swiss cheese on top, and return to the oven for 15 minutes until cheese is melted and bubbly.
08 -
Allow the meatloaf to rest for 10 minutes before slicing and serving.