Start the onions: Melt the 2 tablespoons of butter in a large frying pan over a medium-low heat. Add the sliced onions and the pinch of sugar. Stir them gently, then leave them to cook slowly. You are looking for them to become soft, golden, and sweet — this should take about 20 minutes. The smell will become sweet and rich, and the sound will be a gentle, happy sizzle.

Make the patties: While the onions do their thing, combine the beef mince, onion powder, garlic powder, Worcestershire sauce, and a generous seasoning of salt and pepper in a mixing bowl. Divide the mixture in half and shape into two thin, oval patties, slightly larger than your bread slices. They will shrink as they cook. The mince should feel cool and supple in your hands, and the Worcestershire sauce gives it a dark, savoury promise.

Cook the patties: Once the onions are done, remove them from the pan and set them aside. Turn the heat up to medium-high. Add a tiny bit more butter if the pan looks dry. Place the patties in the hot pan and let them cook undisturbed for 3-4 minutes. Listen for a vigorous sizzle — that is the sound of a good crust forming. The bottom of the patty will turn a deep, dark brown. Flip them and cook for another 2-3 minutes for medium. After testing this recipe five times, I finally got it just right.

Prepare the bread: While the patties are resting, spread a thin layer of mayonnaise on one side of each slice of rye bread. This is the secret to achieving a perfectly golden, crisp crust instead of using butter, which can burn.

Assemble the melts: Wipe the pan clean and return it to a medium heat. Place two slices of bread, mayo-side down, in the pan. Top each with a slice of Swiss cheese, a cooked patty, a generous pile of caramelised onions, and another slice of Swiss cheese. Place the remaining bread slices on top, mayo-side up.

Grill to perfection: Cook the sandwiches for 2-3 minutes per side, pressing down gently with a spatula. You will hear a gentle hiss as the bread toasts. The cheese will begin to ooze from the sides, and the colour of the bread will turn a gorgeous, even golden brown. Flip carefully and repeat on the other side until the cheese is fully melted and the bread is deeply toasted.

Rest and slice: Remove the patty melts from the pan and let them sit on a cutting board for just one minute. This allows the cheese to set slightly, preventing it from all sliding out when you cut. Slice each sandwich in half on the diagonal. The sight of the gooey cheese stretching as you cut is the final, glorious cue that you are about to eat something wonderful.