Place 2 pieces of matzo in a square dish filled with water for 10 seconds, turn over and soak another 10 seconds. Remove from water and set aside.
Beat 3 large eggs. Add salt and pepper to taste. Set aside.
Defrost frozen pepperoni slices. Slice mushrooms. Heat a tablespoon of butter over medium heat and add mushrooms. Cook for 5 minutes and add pepperoni. Cook another 5 minutes and remove to bowl.
Heat another tablespoon of butter in pan (or butter/oil combo). Break up matzo and add to pan. Stir and flip until coated with butter (add more butter if desired).
Pour egg mixture into pan and stir to coat, spreading into an even layer. Cover with lid and turn heat too low. Cook 5 minutes.
Use a plate to remove matzo from pan. Flip over and return to pan.
Add tomato sauce and spread evenly. Add mushrooms, pepperoni and spread grated cheese over top. Place lid back on and keep covered until cheese is melted and bottom is crisp.
Remove from pan. Let cool a few minutes before cutting into slices.