Preheat oven to 375°.
Place chopped tomatoes in a single layer on paper towels. Sprinkle with salt and let sit for 20-30 minutes.
Prepare pie crust and press into a 9" pie plate
Line piecrust with aluminum foil or parchment paper. Weigh down by filling with pie weights or dried beans to keep the pie shell from bubbling up.
Bake at 375° for 15-20 minutes until slightly browned.
Remove weights and cool completely.
Dry off tomatoes and squeeze out excess water (super wet tomatoes will make for a soggy pie crust)
Mix mayonnaise, cheeses, and optional hot sauce.
Layer diced onions in cooled piecrust, season with salt, pepper, and basil.
Top with mayonnaise mixture.
Sprinkle with additional basil. (optional)
Using foil, shield the edges of piecrust to avoid burning.
Bake at 375° for 30-40 minutes until lightly browned.
Let cool for at least 20 minutes before serving.