Remove rolls from package and slice horizontally, as if you were cutting one big roll, so that you have one large top portion, and one large bottom portion.
Spread mustard over both halves of rolls.
Cut cheese slices into quarters and arrange two quarters over each individual roll, for both the top and bottom sections.
Layer 2 pieces of ham, folding as needed, over each individual roll, on the bottom section only.
Carefully flip top section over on top of bottom section, lining up individual rolls.
Place entire rectangle of sandwiches into a disposable aluminum roasting or steam table pan (make sure it is about 3 inches deep).
Combine ingredients for topping and gently brush over top of sandwiches.
Cover pan with aluminum foil. Refrigerate for up to 3 days, or freeze for up to 1 month. (If freezing, be sure to pull the pan out to thaw overnight in the refrigerator before baking.)
Bake, covered, in a 400 degree Fahrenheit oven for 20-25 minutes, until the cheese is fully melted and sandwiches are heated through.