Set your Blackstone griddle to medium-high heat and lightly coat it with vegetable oil. Add sliced onions to the griddle with 2 tablespoons of butter.

Divide the ground chuck into 8 even portions, about 4 ounces each, and roll them into balls. Keep handling to a minimum to ensure the best texture.

Place the burger balls on the hot griddle. Lay a small piece of parchment paper on top of each and smash them flat using a heavy spatula or burger press to about 1/4 inch thickness. Cook for 2-3 minutes without moving them to get a crispy crust.

Sprinkle each patty with equal parts salt, pepper, garlic powder, and onion powder. Then, using a metal spatula, flip each patty and cook the other side for another 1-2 minutes.

Immediately after flipping, place a slice of cheese on each patty. Allow it to melt as the patty finishes cooking.

Melt the remaining 4 tablespoons of butter on the griddle and place your buns, face down, directly on top. Toast for about 2-3 minutes until they're lightly browned and slightly crispy.

Start with the bottom bun, add your cooked patty with melted cheese, followed by caramelized onions, and any other toppings you desire. Repeat with a second patty and cap it off with the top bun. Serve immediately.