1-First Step: Mise en place: Start by slicing 1 large onion thinly. Portion ground beef into two 1/3-pound patties, about 1/4-inch thick for even cooking. Season both sides generously with salt and pepper. Slice Swiss cheese and butter rye bread slices lightly on one side each. Gather Thousand Island dressing if using. This prep takes 5 minutes and sets you up for smooth assembly.

2-Second Step: Caramelize the onions: Heat 2 tablespoons butter in a skillet over medium-low heat. Add sliced onions and cook, stirring occasionally, for 20-25 minutes until soft, golden, and sweet. Learn more about their perks via this guide to onion benefits. Season lightly with salt. Remove from pan and set aside. This slow cook builds the signature patty melt with caramelized onions flavor.

3-Third Step: Cook the patties: Increase skillet heat to medium-high. Add patties and cook 3-4 minutes per side for medium doneness (internal temp 160°F). They should develop a nice crust. Remove to a plate. Wipe skillet if needed, but keep flavorful bits.

4-Fourth Step: Assemble the sandwich: Place one buttered rye slice butter-side down in the skillet over medium heat. Layer: one beef patty, one Swiss cheese slice, half the caramelized onions, another cheese slice, then top bread slice butter-side up. Optional: spread Thousand Island on the inside of top bread for tang.

5-Fifth Step: Grill to perfection: Cook 2-3 minutes until bottom is golden and crispy. Press gently with a spatula or heavy pan for even contact. Flip carefully and grill other side 2-3 minutes. Cheese should ooze and bread toast fully. Repeat for second sandwich. Use medium heat to avoid burning while melting cheese thoroughly.

6-Final Step: Rest and serve: Let patty melts rest 1 minute on a cutting board. Slice diagonally for easy eating. Pair with fries, pickle spear, or simple salad. Enjoy hot for best texture. This method yields diner-quality results every time.