Cooking Instructions

• In a large cast-iron skillet set over medium to medium heat, add 1 tablespoon of butter and sliced onions. Cook onions, stirring occasionally, for about 25 minutes until they are a deep brown color. If the onions are burning on spots, you might need to turn your heat down to medium-low.
• Near the end of cooking (about 5 minutes), add apple cider vinegar and stir to combine. Then remove from the skillet.
• Shape ground beef into two thin 4-ounce patties. Season patties with salt and pepper.
• When onions are done, set the heat to medium-high and add the patties. Cook for 3 minutes per side until done. Remove patties.
• Wipe your skillet clean and add the last tablespoon of butter. Once melted, add all bread slices to the skillet, buttering one side of each slice.
• Remove two slices of bread and build sandwiches with cheese, patties, and onions on the remaining bread in the skillet, then top with the buttered bread slices.
• Cook over medium-low heat for 3 to 4 minutes per side until the bread is toasted and cheese is melted.
• Slice sandwiches in half and serve immediately while warm.