Start the Bacon: Add the chopped bacon to a medium saucepan over medium heat and cook until the fat renders and the bacon is starting to crisp, about 8 to 10 minutes. Spoon the bacon pieces onto a plate, leaving the bacon fat in the pan.
8 ounces thick-cut bacon
Slow-Cook the Onions: Add the butter to the bacon fat, then pile in the sliced onions. Drop the heat to medium-low and cook, stirring often, until the onions turn deep golden and super soft, about 45 to 60 minutes. If they’re browning too fast, lower the heat and keep going.
3 tablespoons unsalted butter, 4 large yellow onions
Turn It Into Jam: Stir the bacon back into the onions. Add the brown sugar, vinegar, black pepper, and the ¼ teaspoon salt. Simmer 10 to 15 minutes, stirring frequently, until thick, glossy, and spoonable. Take it off the heat and let it cool slightly so it doesn’t lava-burn your mouth later.
½ cup packed light brown sugar, ½ cup apple cider vinegar, ½ teaspoon freshly ground black pepper, ¼ teaspoon kosher salt
Mix the Pickle Mayo: In a mixing bowl, stir together the mayonnaise, chopped pickles, and pickle juice. Set aside (or refrigerate if you’re waiting).
1 cup mayonnaise, ¾ cup dill pickles, 1 tablespoon pickle juice
Form the Patties: Divide the brisket into 8 equal portions and gently shape into patties. Season both sides with the 2 teaspoons salt and 1 teaspoon pepper.
3 pounds ground brisket, 2 teaspoons kosher salt, 1 teaspoon freshly ground black pepper
Sear the Burgers: Heat a cast iron skillet over medium-high heat. Cook the patties until deeply browned, about 3 to 4 minutes per side, depending on thickness.
Melt the Cheese: Top each patty with two slices of Monterey Jack. Cover the skillet with a lid for 30 to 60 seconds, just until the cheese is fully melted.
16 slices Monterey Jack cheese
Toast the Buns: Spread the softened butter on the cut sides of the buns and toast them cut-side down in a skillet until golden.
2 tablespoons unsalted butter, 8 sesame seed burger buns
Assemble Like You Mean It: Spread pickle mayo on the bottom buns, add a pile of shredded lettuce, then the cheesy patties. Spoon bacon-onion jam over the top, add more pickle mayo if you want, and cap with the bun tops.
3 cups shredded iceberg lettuce
Serve Immediately: Eat right away while everything is hot and melty. Napkins are mandatory, and that’s not a suggestion.