Prepare your bread: Slice the Cuban bread horizontally, lengthwise. If using a baguette, do the same. You want to create a top and bottom half.
Assemble the sandwich: Spread a generous layer of yellow mustard on the inside of both halves of the bread. On the bottom half, layer the thinly sliced roasted pork, followed by the sweet ham. Top the ham with the Swiss cheese slices, and then arrange the dill pickle slices over the cheese.
Close the sandwich: Place the top half of the bread over the fillings. Press down gently.
Butter the bread: Spread the softened butter evenly over the top and bottom of the assembled sandwich. This is key for achieving that perfect golden-brown crispness.
Press the sandwich: Heat a panini press according to manufacturer's instructions. Place the buttered sandwich in the press and close the lid. Grill for about 5-7 minutes, or until the bread is golden brown and crispy, and the cheese is melted and gooey. If you don't have a panini press, heat a large cast-iron skillet or griddle over medium heat. Place the sandwich in the skillet and weigh it down with another heavy skillet or a foil-wrapped brick. Grill for about 3-4 minutes per side, until golden brown and the cheese is melted, pressing down occasionally.
Slice and serve: Carefully remove the sandwich from the press or skillet. Let it rest for a minute before slicing it diagonally into two or three portions. Serve immediately and enjoy the symphony of flavors!