Place a large skillet over medium heat. Add a small amount of butter.
Slice the baguette in half lengthwise. Spread 1 tablespoon butter evenly on one half of the bread and the mustard on the other. Layer the ham, roast pork, cheese and pickles on the bottom half; close with the top.
Place the sandwich in the skillet and press down with your hands, a spatula or another skillet; cook for about 30 seconds, flip and cook on the other side until golden and the cheese is melted. Slice in half.