Follow these straightforward steps to craft your Onion Burger In-N-Out Style:

1. Prepare the Onions: In a skillet, melt 2 tablespoons of butter over medium heat. Add the sliced onions, sprinkle with salt, and sauté until they are golden brown and caramelized, about 15-20 minutes.

2. Season the Beef: While the onions are cooking, divide the ground beef into four equal portions. Gently form each portion into a patty, making a small indentation in the center to prevent puffing during cooking. Season both sides with salt and pepper.

3. Cook the Patties: Heat a grill or skillet over medium-high heat. Place the patties on the grill and cook for about 3-4 minutes on one side. Flip the patties and place a slice of American cheese on top. Cook for an additional 3-4 minutes or until the cheese is melted and the burger reaches your desired doneness.

4. Toast the Buns: While the burgers are cooking, cut the hamburger buns in half and toast them on the grill or in a separate skillet until golden brown.

5. Assemble the Burgers: Once the patties are cooked, place each patty on a toasted bun. Top with a generous amount of caramelized onions and any additional toppings you desire.

6. Serve Immediately: Close the burgers with the top bun and serve hot with your favorite sides.