Butter one side of both slices of bread. Make sure you spread the butter to the edges so nothing sticks.
Place the buttered side of the bread down on the inside of the mountain pie maker.
Spread the pizza sauce on the slice of bread that's in the mountain pie maker.
Sprinkle mozzarella in the center of the bread and carefully spread it towards the edges. Leave a little space around the edges.
Add the slices of pepperoni on top of the cheese.
Place the other slice of buttered bread on top of the pepperoni with the butter side up.
Press the top of the pie iron down on the bread making sure all of the bread is stuffed inside the iron. Clip it shut.
Put the pie iron in the hot coals. Let it sit for about a minute and then open it up to check on it. This is the only way to know if you're burning your mountain pie. Once one side is golden, flip the pie iron over and brown the other side.
Pop the pie out of the pie iron onto a plate and let cool for at least 1 to 5 minutes.