Lay tomato slices out onto a paper towel lined baking sheet in a single layer. Sprinkle with salt and let stand 10 minutes to draw out moisture. Reserve some slices for decorating top, if desired.
Layer tomato slices, onion, and basil into the pie shell. Season with black pepper.
In a small mixing bowl, stir together cheddar cheese, mozzarella cheese, parmesan, mayonnaise, and sour cream. Spread over the top of the tomatoes to cover the top of the pie. Arrange decorative slices on top, if desired.
Bake in the preheated 375 degree oven for about 30 minutes, until cheese is lightly browned. Serve hot.