Ingredients

You can check off items on the list below as you complete your ingredients list!

Instructions

1. 1. Combine all sauce ingredients in a small bowl and set aside.
2. 2. Melt 1 tbsp butter in a large heavy-based pan over medium heat. Add the onions and fry until they start to soften and turn golden, around 8-10 minutes.
3. 3. Lower heat and season the onions with a pinch of salt & pepper. Continue frying for another 15 minutes, or until completely soft and golden brown. If they start to dry out/catch on the pan, just add water 1 tbsp at a time. Remove the onions from the pan and raise the heat to medium-high.
4. 4. Spread one side of each slice of bread with butter. Place them butter-side-down in the pan and toast until crisp and golden. Remove and place them toast-side-up and turn off the heat. Place Swiss on half of them and American on the other half.
5. 5. Gently shape the burger patties into a square, slightly larger square than your bread. Don't overwork the meat, just enough to shape it accordingly. Generously season the top side with salt & pepper.
6. 6. Melt 1 Tbsp butter in the pan over medium-high heat then add the patties seasoned-side-down. Season the top, then leave to fry for a couple of mins, or until they build up a crust on the bottom. Flip them over and cook until you build a crust on the second side and they're just about cooked through. Remove them from the pan and turn off the heat.
7. 7. Spread all 4 slices with sauce, then stack two of them with the patty and onions. Add the second slice on top to create two sandwiches (both with half American and half Swiss cheese).
8. 8. If desired, clean out your pan and add 2 Tbsp butter. You can also do this step using the fat from the burgers. Add the sandwiches to the pan and toast both sides as you would a grilled cheese. Cook until golden brown on the outside, with the cheese starting to melt.
9. 9. Remove, slice each sandwich in half and enjoy!