Preheat oven to 400. Lay pie crust rounds side by side, overlapping according to the size of your pan.
Trim excess of overlap and gently roll seam into one large rectangular dough.
Ease into baking dish, leaving the sides high and folding/adjusting to fit.
Prick dough with tines of a fork
Place a piece of foil over bottom and up sides of dish, and fold foil edge over rim in several places to secure.
Fill foil with beans or pie weights.
Bake for 12-14 minutes and remove from oven. Carefully remove foil and set aside. Let crust cool slightly.
Turn oven down to 350.
Slice tomatoes and lay on a double layer of paper towels. Sprinkle with salt. Let sit 30 minutes. Pat tops with additional paper towels. Repeat. Season with salt and pepper after final pat dry.
Separate egg and use egg white to brush over the inside bottom of pie crust dough. Let dry. Mix the yolk with the mayonnaise.
Saute onion in butter and olive oil until it begins to caramelize, about 15 minutes. Add peppers and cook until pepper is softened. Remove from pan and set aside. Add sausage to skillet and cook until browned. Drain well on paper towels.
Assemble pie by sprinkling panko crumbs over bottom of pie crust. Top with a thin layer of Parmesan. Layer in 1/2 of the tomatoes. Top with 1/2 of sausage and vegetables. Dot with 1/2 of mayonnaise mixture and sprinkle with 1/2 of cheeses. Repeat layers, Top pie evenly with pepperoni slices. At this point the dish can be refrigerated for several hours before baking.
Bake at 350, loosely covered, for 30 minutes, then uncover and continue baking for 30 more minutes or until pie is set and golden. Let cool for 10 minutes before cutting to serve.
