01 -
Melt butter in a medium skillet over medium-high heat. Add sliced onions and cook, stirring occasionally, until caramelized, about 10 minutes. Reduce heat if onions begin to burn.
02 -
Transfer caramelized onions to the bottom of a 5-6 quart slow cooker.
03 -
In a large bowl, combine lean ground beef, beefy onion soup mix, Italian bread crumbs, eggs, milk, and Worcestershire sauce. Dice five slices of Swiss cheese and incorporate into mixture thoroughly.
04 -
Shape the mixture into a loaf using clean hands. Place the loaf atop the caramelized onions in the slow cooker.
05 -
Pour condensed French onion soup evenly over the loaf in the slow cooker.
06 -
Cover and cook on low for 5 to 6 hours or on high for 3 hours, until the internal temperature reaches 165°F.
07 -
Five minutes before serving, top the meatloaf with the remaining three slices of Swiss cheese. Replace lid and allow cheese to melt.
08 -
Optionally garnish with chopped parsley. Slice and serve, optionally pouring some cooking juices over the slices.