Prep tomatoes: Begin by slicing your ripe tomatoes and laying them out on a couple of paper towels. Sprinkle them lightly with salt to remove excess moisture. Let them sit for about 10 minutes, then gently pat them dry with another paper towel.
Preheat oven: Preheat to 375°F.
Roll: Roll out the pie crust and then place in a pie dish. Crimp the edges. Poke the bottom of the crust with a fork. Place in the oven and par-bake for 10 minutes.
Layer: Place the tomatoes, onion and basil into the pie crust. Season the top with salt and pepper.
Combine: Mix together the mayo, garlic powder, Italian seasoning and cheese in a bowl. Gently spread on top of the tomatoes.
Bake: Turn oven to 350°F and then bake pie for 25-30 minutes, or until the top is lightly golden brown. Remove from oven and allow to set for 15 minutes on a cooling rack. Slice and serve warm.