Preheat pan to medium.
Brush bread with garlic butter, place face down on pan and smash, flip when it becomes golden, then toast until crispy.
Add diced onion and butter to pan on medium and stir until onions caramelize.
Season ground beef and separate it into 2 equal pieces.
Add to pan on high then smash with parchment paper and spatula.
Flip parties and cook until desired then add cheese.
Assemble burger by adding bun, sauce, patty, patty, onions, sauce, and top bun in order.
Enoy!
