Form the ground beef into a tight ball, 5.5 ounces per ball.
Heat a flat-top griddle to very high heat.
Season hamburger ball all over with salt and pepper.
Add a little oil to griddle then place hamburger ball on flat top and flatten with a metal spatula.
Flatten to approx 1/3 inch thickness.
Cook for 1 1/2 minutes to develop a crust on the first side until blood floats to the top.
Flip over and cook for 1 more minute on the second side to develop a crust on that side.
Add cheese sauce to the top of the hamburger and top with the slice of American cheese.
Place a dome lid over the top of the burger.
Pour the mixture of stock/water on to the flat top so the liquid runs under the dome and creates steam to cook the burger and melt the cheese.
Cook for 3 minutes until cheese has melted completely then remove dome.
Melt butter with garlic and season with salt. Brush inside of bun halves and toast on the griddle for 3-4 seconds until golden and crisp.
Flip and toast for 3-4 seconds so the outsides are also lightly toasted.
To assemble, smear Donkey Sauce
on cut-side of both bun halves.
Layer base with pickle slices and hamburger patty.
Top with Rojo Onion ring, BBQ Sauce, shaved onions, tomato, lettuce then place the top half of the bun on top.