01 -
Heat olive oil and 1 tablespoon butter in a skillet over medium heat. Add the sliced onions and cook slowly, stirring frequently, for 15–20 minutes until they are soft, golden, and deeply caramelized. Season with salt, pepper, and a splash of Worcestershire sauce. Remove onions from the skillet and set aside.
02 -
Combine ground beef with salt, pepper, and garlic powder. Shape into 2 thin patties sized to fit the bread slices. In the same skillet, cook patties for 3–4 minutes per side, or until cooked to your preference. Transfer meat to a plate and set aside.
03 -
Wipe the skillet clean. Spread butter on one side of each bread slice. Place one slice, butter-side down, in the skillet. Layer with cheese, a beef patty, caramelized onions, another cheese slice, and top with the second buttered bread slice, butter-side up.
04 -
Cook sandwiches over medium heat for 2–3 minutes on each side, gently pressing, until the bread is golden and crisp, and cheese is fully melted. Repeat for the second sandwich.
05 -
Slice each patty melt in half. Garnish with fresh thyme or parsley as desired. Serve immediately.