Step 1

Slice the onions very thinly.

Step 2

Heat the olive oil in a large skillet over medium low heat. Add the onions and season with a bit of salt and pepper.

Step 3

Cook over medium low to low heat, stirring occasionally, until soft and caramelized, about 45 minutes. Set aside but keep warm.

Step 4

Cook the bacon until crispy-chewy. You don't want it totally crispy so it shatters when you bite it. Set aside, reserving the bacon fat.

Step 5

Brush the cut sides of the brioche buns with a thin coating of bacon fat. Toast them, cut side down (or broil them, cut side up) until golden brown. Set aside.

Step 6

Stir together the mayonnaise, Worcestershire sauce and black pepper (as much as you like). Set aside.

Step 7

Divide the chuck into 8 2-oz patties and lightly roll each portion into a ball.

Step 8

Heat your ungreased griddle over medium high heat until very hot, about 10 minutes.

Step 9

Place 2 of the portions (or 4 if you're fancy and your surface is big enough) onto the griddle and press them down firmly until they are flat. Use your spatula to thin out the edges even more so they get extra crispy. Season each patty with some salt and pepper, and sear for about 1 1/2 minutes or until there are several "done" spots on top of the patties and the edges are getting crispy.

Step 10

Use your scraper to scrape up each burger and flip each patty. Immediately top each one with a slice of American cheese. Top 1 of the patties (or 2 if you're fancy) with 1/4 of the caramelized onions (or to taste).

Step 11

Let the burgers cook about 30 seconds, and then stack a cheese-topped patty on top of a cheese-and-onion-topped patty. Place in a 200F oven or toaster oven to keep warm.

Step 12

Finish cooking all patties in the same way. When you're done, you'll have 4 stacks of two cheese-topped patties with a layer of caramelized onions in between.

Step 13

Spread 1 Tablespoon of the mayonnaise mixture on both sides of each bun. Place 3 slices of bacon on each bottom bun and top with a "burger stack" and the top bun.

Step 14

Wrap each burger in a sheet of foil and allow to steam for 2-3 minutes. This will reheat the bun and make it nice and soft.

Step 15

Serve immediately. You can add extra toppings of your choosing if you like, but wow, is this combo fantastic all by itself!