Slice the Crusty French Roll horizontally, leaving a hinge if you like so the sandwich holds together.
Spread a thin layer of softened Butter on both cut faces of the roll to add flavor and help toast the bread.
Pile generous slices of Bologna-Style Mortadella onto the bottom half, folding slices as needed to create a thick, even layer.
Smear a thin stripe of Yellow Mustard on the top half of the roll (adjust amount to your taste).
For a warm sandwich, heat a skillet over medium heat and place the assembled sandwich butter-side down; press gently with a spatula or a weighted pan and cook 2–3 minutes per side until the bread is golden and the edges of the mortadella begin to crisp.
If you prefer it cold, simply close the sandwich and serve immediately.
Cut the sandwich in half and serve right away while the crust is still crisp.
