Cut the top of your bread 1/2" down saving the top. Scoop out the inside of your bread to 1/4" of bread left inside. Spread your mustard around all sides of the bread including the top.
Layer your meats and chesses alternately, using a mild cheese and a stronger deli meat i.e. swiss and capacoli go well together. Make sure to run your layers all the way up the sides of the bread. Your top layer should be cheese.
Place the top back on your sandwich and wrap tightly with plastic wrap. Allow 3-4 hours or overnight to set up in the fridge.
Cut into wedges as you would a cake. No mess eating!