Cut the crusts off the bread. Using a rolling pin, roll out the pieces of bread until flat.
Place a cheese stick or 2 tablespoons of cheese on the edge of the bread closest to you. Place 3 slices of pepperoni, if using, on the bread above the cheese. Tightly roll up the bread, pressing the seam end to adhere.
Melt the butter in a sauté pan over medium heat. Cook the roll-ups seam-side down until golden, 1 to 2 minutes. Flip and cook until golden all over, 1 to 2 more minutes.
Cut each roll-up into pieces and serve with the sauce for dipping.