01 - Grate the peeled potatoes using a box grater. Gather the shredded potatoes in a clean kitchen towel and wring out as much moisture as possible. Transfer the dried potato shreds to a mixing bowl.
02 - Add the melted butter, vegetable oil, garlic powder, onion powder, salt, and pepper to the grated potatoes. Toss everything together until the seasonings are evenly distributed throughout the mixture.
03 - Heat a large nonstick skillet or griddle over medium-high heat. Divide the potato mixture into 4 equal portions. Press each portion into a thin patty roughly 4 inches in diameter. Place the patties on the hot skillet and cook for 3 to 4 minutes per side until deeply golden and crisp. Remove from the pan and keep warm.
04 - Gently shape the ground beef into 4 loose balls, being careful not to overwork the meat. Heat the skillet or griddle over high heat. Once the surface is ripping hot, set the beef balls on the skillet and immediately smash each one flat with a heavy-duty spatula or burger press. Season the top generously with salt and pepper.
05 - Cook the smashed patties for 2 to 3 minutes until the bottoms develop a dark crust and the edges turn crispy. Flip each patty, lay a slice of cheddar cheese on top, and continue cooking for 1 to 2 minutes until the cheese is fully melted.
06 - Spread burger sauce on the bottom half of each toasted bun. Layer on a lettuce leaf, a tomato slice, and a few rings of red onion. Set a crispy hash brown patty on top, followed by the cheesy smash burger. Scatter pickle slices over the patty and crown with the top bun.
07 - Serve the burgers immediately while hot so the hash browns stay crunchy and the cheese remains gooey.