"Pickled" Patty Melt Paninis

In a medium-sized bowl, mix together the ground beef, onion powder, salt, and pepper. Divide the mixture into four equal-sized portions. Form each portion into a square-shaped patty. Warm a stovetop panini press or nonstick skillet over medium-high heat. If using a panini press, close lid and grill beef patties for about 5 minutes until medium-rare; if using a skillet, cook patties for about 2-3 minutes until they lift up easily from the bottom, then flip and cook for another 2-3 minutes until medium-rare. Set patties aside. Place 4 slices of rye onto a clean, flat work surface. Spread 1 tablespoon of thousand-island dressing onto each slice of rye. Layer atop each slice, in order, 1 slice of Swiss cheese, 4 pickle slices, a beef patty, and another slice of Swiss cheese. Top each sandwich with one of the remaining slices of bread. If using a panini press, grill sandwiches for about 5 minutes until bread is golden-brown and cheese is melted, grilling in batches if necessary. If using a skillet, melt 2 tablespoons of butter in skillet before adding sandwiches, and use a heavy pot lid to press sandwiches down, grilling each side for 2-3 minutes until bread turns golden-brown.