Preparation:

Step 1: Caramelize the Onions

1. Heat a skillet over medium heat and melt 2 tablespoons of butter.
2. Add the sliced onions to the skillet and cook, stirring occasionally, until they become soft, golden, and caramelized. This process typically takes 8–10 minutes.
3. Once caramelized, remove the onions from the skillet and set aside.

Step 2: Shape and Smash the Patties

1. Divide the ground beef into four equal portions and roll each into a small ball.
2. Preheat a skillet or griddle over high heat until it’s very hot. This step is crucial to achieve the signature crispy edges.
3. Place the beef balls onto the skillet and immediately press them flat with a heavy spatula or burger press. The patties should be thin but not falling apart.

Step 3: Season and Sear the Patties

1. Season each patty with salt and black pepper.
2. Cook the patties for 2–3 minutes on the first side, allowing a crispy crust to form.
3. Flip the patties, immediately place a slice of cheddar cheese on top, and cook for another 1–2 minutes until the cheese melts and the patties are fully cooked.

Step 4: Toast the Buns

1. While the patties are cooking, toast the burger buns. Spread a light layer of butter on the cut sides of the buns and toast them in the skillet until golden and crisp.

Step 5: Assemble the Cheesy Smash Burgers

1. Spread a generous amount of burger sauce or mayonnaise on the bottom bun.
2. Place a cheesy patty on top, followed by a layer of caramelized onions.
3. Add the second cheesy patty and any optional toppings like lettuce or pickles.
4. Finish with the top bun and press gently to compact the burger.

Step 6: Serve and Enjoy

Serve the burgers hot with your favorite sides like fries, onion rings, or a fresh salad.