Preheat griddle or large skillet over medium-low heat. Cut the bread in half horizontally and spread both sides with a thin layer of mustard then spread on a bit of mayonnaise, if desired.
Arrange the ham and roasted pork loin evenly on top of the mustard. Divide the cheese slices between the sandwiches then add enough pickles to nearly cover the cheese.
Close the sandwich and spread top and bottom of each bun with butter and wrap sandwiches separately in aluminum foil. Fold the foil around the edges of the sandwiches to completely seal.
Place wrapped sandwiches on griddle or in skillet then place a heavy pot or skillet containing a heavy item (such as a large can of tomatoes) on top of the sandwiches. Press down to compact the sandwiches and allow them to cook undisturbed for about 10 minutes.
Remove the weight from the sandwiches and flip them over. Replace weight and cook about 8–10 minutes more until the cheese has melted and both sides of the bread are crispy. Remove from heat, carefully open foil, slice and serve while hot and crispy.
Don’t have a spare pot or skillet to ‘press’ the Cuban sandwich? You can use any heatproof item if you wrap it in clean aluminum foil first!