- 2 tablespoons butter plus softened butter for bread
- 3 onions, very thinly sliced
- 1 bay leaf
- Salt and ground black pepper
- 1/2 teaspoon ground thyme
- 1/2 cup beef stock
- 1 1/2 pounds 80-90% lean ground beef
- 2 tablespoons Worcestershire sauce
- About 1 teaspoon (1/3 palmful) granulated garlic
- About 1 teaspoon (1/3 palmful) granulated onion
- 1/3 to 1/2 cup (a fat handful) freshly grated Parmigiano-Reggiano cheese
- Olive oil, for drizzling
- 8 slices pumpernickel bread
- Chopped pickled Italian cherry peppers or finely chopped Italian giardiniera (hot pickled vegetables)
- 12 slices deli-cut Provolone cheese
Heat a medium skillet over medium heat and melt 2 tablespoons butter. Add onions, season with bay, thyme, salt and pepper. Cook onions slowly, adding a splash of water if they get dry or brown to quickly, and cook 30 minutes until very soft and sweet. Add stock, remove bay leaf and keep warm over low heat.
Combine meat with salt, pepper, Worcestershire, granulated garlic and onion, Parm and a fat drizzle of oil. Make 4 large, thin patties that are even thinner at the center than the edges for even cooking.
Preheat a cast-iron griddle or large cast-iron skillet over medium-high heat. Cook patties 3-4 minutes on each side then remove, wipe pan clean and reduce heat to medium-low.
Lightly butter one side of the bread slices.
Build sandwiches with buttered sides out: bread, cherry peppers, 2 slices provolone, burger, caramelized onions, provolone and bread.
Grill sandwiches until crispy and the cheese is melted. Serve with Shoestring Oven Fries with Balsamic Ketchup alongside.