Crusty browned beef, cheddar, pickles, and a tangy burger sauce baked into a pan of Hawaiian rolls with a garlic butter and sesame top. The bottoms stay sturdy, even as leftovers.
Heat the oven to 350°F with a rack in the middle. Line a 9x13-inch baking dish with parchment.
Stir the burger sauce ingredients together in a small bowl.
Without pulling the rolls apart, slice the slab in half horizontally with a serrated knife. Set the bottom slab in the dish, cut side up, and toast 5 minutes, until the cut side feels dry.
Heat a large skillet over medium-high heat. Add the beef, press it into one flat layer, and cook without stirring 4 to 5 minutes, until the bottom is deep brown.
Flip the beef in large pieces, break it into small crumbles, and add the onion. Cook 3 to 4 minutes more, stirring only now and then, until no pink remains and the onion is soft. Drain off the fat.
Off the heat, stir in the Worcestershire, garlic powder, salt, pepper, and about a third of the burger sauce.
Sprinkle half the cheddar over the toasted bottom buns. Spread the beef evenly to the edges and press it down firmly. Top with the remaining cheddar and a pickle chip for each slider.
Spread the remaining burger sauce on the cut side of the top slab and set it over the pickles, sauce side down.
Stir the garlic powder into the melted butter. Brush it over the tops and into the cracks, then sprinkle with the sesame seeds and dried onion.
Center the dish on the middle rack and bake uncovered 6 to 8 minutes, until the tops are golden. Cover loosely with foil and bake 4 to 6 minutes more, until the cheese melts.
Rest 5 minutes. Lift out by the parchment, cut along the roll lines, and serve hot.
Notes
Rolls: Any soft slider roll works. Pre-split slider buns work too: set the bottoms in the dish touching, toast, and build the same way.
Browning: Sweet rolls brown quickly. Check at 6 minutes and add the foil as soon as the tops are golden.
Cheese: Sliced cheddar or American works in place of shredded. Use half under the beef and half over it.
For 24 sliders: Double everything, use a half sheet pan or two 9x13 dishes, and brown the beef in two batches.
Bacon cheeseburger sliders: Add crumbled crisp bacon over the beef before the top layer of cheese.
Lactose free: Use aged cheddar or lactose-free cheese, lactose-free butter or olive oil in the topping, and a dairy-free roll if needed.
Make ahead: Cook and season the beef up to 2 days ahead and refrigerate. Build and bake just before serving, adding a few minutes under the foil.
Storage: Refrigerate leftovers in an airtight container for up to 3 days.
Reheating: Cover loosely with foil and warm in a 350°F oven for about 10 minutes, or microwave about 30 seconds per slider.