Preheat oven to 250ºF.
Arrange tomato slices on a baking sheet and drizzle with EVOO, oregano, salt and pepper. Roast in oven until beginning to caramelize, 1 hour, then turn oven up to 325ºF for another 30 minutes. Remove tomatoes from oven and allow to cool slightly.
If using fresh pizza dough, turn oven up to 450ºF. Roll dough out to about 12-inches in diameter across on a lightly floured surface. Transfer dough to a cookie sheet and bake in oven until golden brown, 10-12 minutes. Let cool.