Found on the Internet, not from a source I've known before, but it's such a simple straightforward recipe that it can't really be problematic. The most likely cause for failure would just be that the tomatoes are too juicy and you end up with a soggy pie, which actually can happen with regular fruit pies as well. I'm thinking some garlic would go well with this too, possibly garlic oil. I also like sprinkling fresh basil on top of stuff like this - raw basil is a lot punchier than when it's baked.
Ingredients
5 roma tomatoes, peeled and sliced (or whatever you have)
10 fresh basil leaves chopped
1/2 cup green onion (or red onion) chopped
1 9-inch pre-baked pie crust
1 cup shredded mozzarella cheese
1 cup freshly shredded cheddar cheese
3/4 cup mayonnaise (or half mayo, half Greek yogurt)
2 Tablespoons freshly grated parmesan cheese
salt and freshly ground black pepper
Instructions
1. Preheat oven to 350 degrees F. Place the tomatoes in a colander in the sink in a single layer. Sprinkle with salt and allow them to rest for 10 minutes.
2. Use a paper towel to pat-dry the tomatoes and make sure most of the excess juice is out. (You don't want wet (juicy) tomatoes or your pie will turn out soggy).
3. Layer the tomato slices, basil, and onion in pre-baked pie shell. Season with salt and pepper.
4. Combine the grated cheeses and mayonnaise or Greek yogurt together. Spread mixture on top of the tomatoes and sprinkle parmesan cheese on top.
5. Bake for 30 minutes or until lightly browned. Allow to rest for at least 15 minutes before cutting and serving.