Preheat oven to 400°F. Prick pie crust with a fork, bake 10 minutes, and remove from oven.
Reduce heat to 325°F. Pat tomatoes down with paper towel. Cover bottom of crust with 2 layers of tomatoes. Sprinkle on half the scallions, oregano, and basil and season with salt and pepper.
In a bowl, combine the cheddar cheese and mayonnaise, mix till well blended, and spread half the mixture over the tomatoes.
Repeat layering with the remaining tomatoes, scallions, oregano, basil, salt, pepper, and mayonnaise spread. Top with Parmesan cheese and bake till golden and firm, about 45 minutes. Let pie cool slightly before slicing.