Form the Meat Patties
Divide the ground beef into three equal portions (about 5.3 oz each) and shape them into flattened patties. Make sure they are roughly the same size as your bread slices to ensure even coverage. Press down slightly in the center of each patty to prevent it from puffing up during cooking.
Season the Meat
Sprinkle both sides of each patty evenly with onion powder, garlic powder, salt, and pepper. Press the seasonings gently into the meat to ensure they adhere well and provide maximum flavor.
Cook the Patties
Heat a skillet over medium-high heat until hot. Place the seasoned patties in the skillet and cook for approximately 3-4 minutes on each side for medium doneness, adjusting time as needed for your preferred level of doneness. Once cooked, remove them from the pan and set aside on a plate to rest briefly.
Prepare the Secret Sauce
In a small bowl, combine mayonnaise, chopped bacon pieces, ketchup, sugar, and relish. Stir until all ingredients are thoroughly incorporated and the mixture has a consistent color. This sauce can be made ahead and refrigerated for enhanced flavor.
Assemble the Patty Melts
Wipe the skillet clean with a paper towel and reduce the heat to medium. Butter one side of each bread slice generously. Place three slices buttered side down in the skillet. Layer each slice with a slice of provolone cheese, a cooked meat patty, and a slice of cheddar cheese.
Add the Secret Sauce
Take the remaining three bread slices and spread a generous amount of the secret sauce on the non-buttered side. Place these slices sauce side down on top of the cheese and patty assembly, with the buttered side facing up.
Toast and Serve
Allow the sandwiches to cook until the bottom bread is golden brown and the cheese begins to melt, about 2-3 minutes. Carefully flip each patty melt using a spatula and cook the other side until it reaches a beautiful golden brown color, approximately 2-3 minutes more. Remove from heat, cut diagonally if desired, and serve hot.