Preheat oven to 400 degrees Fahrenheit. Grease a baking pan or line with foil and then grease.
2
Chop pepperoni slices into pieces. Mix tomato paste with enough water to make a thick sauce. Season as desired
3
Spoon tomato mix into pepper, top with cheese, pepperoni, and mushroom slices mixed together Season as desired. Bake for 10-15 minutes, or until cheese is lightly browned and bubbling.