Start building your sandwiches by placing four slices of sourdough bread on the counter Cover each slice of bread with a total of 2 cheese slices on each slice of bread.
Place the pepperoni on top of the american cheese on each of the bottom slices of the sourdough.
spread about 1 ounce of pizza sauce on top of the pepperoni on each sandwich
Place half the mozzarella on top of the pizza sauce on each sandwich.
Top the two finished sandwiches halves, with the other piece of sourdough that you have cheese already on, with the cheese facing the pepperoni.
Melt the butter in a small pan over low heat, then using a pastry brush, brush one side of each of the sandwiches liberally with the melted butter
Heat your pan on the stove top until it is hot enough to toast the bread.
Place the buttered side down on the pan.
Turn heat down to medium, and cover the sandwich with a pot lid to keep the heat in and help the cheese to melt. After about 3-4 minutes check the bread on the pan to see how the color is. It should be toasted a dark golden brown.
Brush butter on the side that is up, then turn it over to repeat the process of toasting the bread. (Use the pot lid again to help melt the cheese) After 3-4 minutes check that side, to see how the color is.
If the cheese is not fully melted, turn the heat down to low and keep the lid covering the sandwich until the cheese has melted. Just be careful not to burn the bread.
Place sandwich on plate, cut in half, serve and enjoy!