In a skillet, heat 2 tablespoons of olive oil over medium heat. Add 2 cups of thinly sliced onions and a pinch of salt, sautéing them for about 10 minutes until golden brown.

In a mixing bowl, combine 1 pound of ground beef with salt, pepper, and half of the minced garlic (about 2 cloves). Form into patties.

Push the onions to the side of the skillet and cook the beef patties for 4-5 minutes on each side until browned and cooked through.

In a small bowl, mix 2 tablespoons of softened butter with the remaining minced garlic and 1 teaspoon each of dried thyme, oregano, and basil to create garlic herb butter.

Place slices of cheddar cheese over the patties and cover the skillet to melt the cheese for about 1-2 minutes.

Spread garlic herb butter on one side of each slice of sourdough bread and toast in a skillet for 3-4 minutes until golden brown.

Assemble the sandwich with one slice of toasted sourdough facing down, cheese patty, caramelized onions, and another slice on top, butter-side up. Press gently to combine.