Logan County Hamburgers

These were good and I especially liked the bread toasted. From "The Comfort Table" by Katie Lee Joel

1 lb. ground beef
1 large egg, lightly beaten
1 medium yellow onion, half grated, half sliced
1/4 tsp. garlic powder
1 tsp. kosher salt
1 tsp. black pepper
12 slices white bread
2 Tbsp. unsalted butter, softened
12 slices American cheese

Combine beef, egg, grated onion, garlic powder, salt and pepper. Mix until combined. Form into thin patties. Spread butter on one side of bread. Cook burgers in a skillet over medium high heat. Drain on paper towels. Drain grease from the skillet. In the same skillet, place 6 slices of bread, butter side down. Top with cheese, some onions and a burger. Top with remaining slices of cheese, and bread, butter side up. Cook until golden brown.