To make the burgers, combine the beef, egg, grated onion, garlic powder, salt and pepper in a medium bowl. Mix until combined then form into 6 thin patties.

Spread the butter on one side of each slice of bread. Heat a large, heavy-duty skillet or griddle over medium-high heat. Cook the burgers about 3 minutes on each side. Drain on paper towels. Drain the grease from the skillet.

In the same skillet, place 6 slices of bread, butter-side down. Top each with a slice of cheese (if using), some sliced onions and a burger. Top with the remaining cheese (if using) and bread, butter-side up. Cook the sandwiches until golden brown, about 2 minutes per side.

Serve with mustard, ketchup, tomatoes, pickles or any other desired hamburger toppings.

Katie’s Short Order Cook Swap Outs: 

Wheat bread for white
Ground turkey for beef
Cheddar or Gruyere cheese for American|

Add bacon as a topping
Mayo or Thousand Island Dressing for, or in addition to, ketchup