Begin by loosely forming 2.5-3 oz balls of ground beef, set onto a tray and place in the fridge to firm for 30 minutes. In another bowl, mix together all the ingredients for your Diner Sauce and set that in the fridge until you are ready.

Preheat your grill to medium high heat (around 350F) adding a cast iron skillet/plancha to the grill 2 minutes before cooking.

Pull your burger patties out of the fridge and add to the skillet. As the meat sizzles, get out a small piece of parchment paper and a larger spatula/burger smasher. Place the parchment over one ball and then firmly press with the spatula until the burger is “smashed” on the skillet. Repeat this for each burger and let cook for another 1-2 minutes. Carefully flip each burger over and then season the new side with salt, pepper and garlic. Pull off and keep warm until ready to use.

Next, add your sliced onions to the skillet and begin caramelizing. Slowly cook the onions until they turn dark brown (about 30-45 minutes). About halfway through the cook, add the salt, pepper, garlic and brown sugar. Stir and keep cooking. Once done, pull off and keep warm.

Start assembling your patty melt with a spoonful of the Diner Sauce on the bottom piece of bread, handful of caramelized onions, sprinkle of gruyere cheese, 1 patty, slice of swiss cheese, another patty, more swiss cheese, caramelized onions, gruyere cheese and another slice of bread with diner sauce. Repeat this for all the patty melts, then place them on a clean skillet/plancha to toast the bread. Cook for 1-2 minutes per side until golden brown, then pull off and let cool.

Serve your patty melts with fries, ketchup and pickles. Enjoy!