01 - Using a box grater, shred the peeled russet potatoes. Gather the shredded potatoes in a clean kitchen towel and wring firmly to extract as much moisture as possible. Transfer the drained potatoes to a mixing bowl.
02 - Add the melted butter, vegetable oil, garlic powder, onion powder, and a generous pinch of salt and pepper to the shredded potatoes. Toss until evenly coated.
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 flat patty about 4 inches in diameter. Cook for 3 to 4 minutes per side until deeply golden and crisp. Remove and set aside on a warm plate.
04 - Gently shape the ground beef into 4 loose balls without overworking the meat. Wipe the skillet clean and return it to high heat. Once the surface is ripping hot, place the beef balls onto 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 edges are browned and 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. Remove from heat.
06 - In a small bowl, stir together the mayonnaise, ketchup, and yellow mustard until well combined. Adjust the ratio to your taste preference.
07 - Spread a generous layer of burger sauce on the bottom half of each toasted bun. Layer on a lettuce leaf, a tomato slice, and a few red onion rings. Place a crispy hash brown patty on top, followed by the cheesy smash burger patty. Add dill pickle slices and crown with the top bun. Serve immediately while hot.