01 -
Heat butter in a skillet over medium heat. Add the sliced onion and salt. Cook stirring occasionally for a few minutes until slightly softened. Add in the sliced pepper. Cook stirring occasionally on low until onions are caramelized, about 20-25 minutes.
02 -
In a bowl, add the ground beef, salt, pepper and garlic powder. Mix and form into four patties.
03 -
Heat 1 tablespoon of butter on a grill pan or cast iron skillet. Once hot, add the patties and cook for 3-4 minutes per side.
04 -
On each slice of bread, spread butter on one side.
05 -
Heat 1-2 tablespoons of butter over medium-low heat in a skillet. Add bread, butter side down and top with 2-3 slices of cheddar cheese and a few tablespoons of shredded Gruyere.
06 -
Top the cheese with the patties, about ⅓ cup of the onion and pepper mix and then divide the remaining cheese among the sandwiches. Add the remaining slices of bread with the butter on the outside.
07 -
Cook the sandwiches for 3-4 minutes per side or until the cheese is melty and the bread is toasted on both sides. Slice the sandwiches in half and serve immediately.