Preheat 2 adjacent zones of the cooktop to medium-high heat for 8 to 10 minutes. Have handy a large, metal spatula and a 5- to 6-inch inch square of parchment paper (to keep the patties from sticking to the spatula).

Divide the beef into 4 equal portions and roll into balls. Season generously on all sides with Traeger Burger Rub, about 1 teaspoon rub per ball.

Drizzle or squirt the oil over the hot surface and use a spatula to spread it evenly. Place the buns cut-side-down on the cooktop and toast until golden brown, 30 to 60 seconds. Set aside for serving.

Place the onions on the hot cooktop and spread in an even layer. Sprinkle with about 1 teaspoon Traeger Burger Rub, then divide the onions into 4 small piles. Let cook just until they start to steam, about 1 minute.

Top each onion pile with a burger ball. For each ball, top with the parchment square, then press down firmly with the spatula to smash the burgers into the onions, creating patties about ¼-inch-thick and just larger than the size of the bun. Cook for 2 to 3 minutes, then flip and cook for another 2 minutes. Top with a slice of cheese and then cover with the steam dome to melt the cheese, about 1 minute. (This may be done 2 at a time if they do not all fit under the dome.) The cheese should be fully melted and become lacy at the edges where it reaches the cooktop. The bottom of the burger should be well browned.

Place pickles on the bottom buns as desired and top with a burger patty and the top bun. Enjoy!