Preheat oven to 350 degrees.

Blind bake the pie crust, so it is not soggy.

Place the tomatoes in a colander in the sink in 1 layer.

Sprinkle with salt and allow to drain for 10 minutes or longer, if you don't the pie will fall apart.

Layer the tomato slices, basil and onion in pie shell.

Season with salt and pepper.

Combine the grated cheeses and mayonnaise together.

Spread mixture on top of the tomatoes and bake for 30 minutes until lightly browned.

To serve: cut into slices and serve warm.