Preheat your oven to 450°F. In a mixing bowl, combine all-purpose flour, granulated sugar, and salt. Cut in cold, cubed butter until the mixture resembles coarse crumbs. Gradually add ice water, mixing until the dough binds together without being tough. Roll the dough into a circle, transfer it to a pie dish, trim the edges, crimp, and prick the bottom with a fork. Sprinkle with parmesan and some mozzarella, then blind bake for about 10 minutes until lightly golden.

While the crust bakes, thinly slice the large tomatoes and lay them on paper towels, sprinkling a little salt on top. Let them drain for 20-30 minutes to remove excess moisture. Meanwhile, grate the cheddar, mozzarella, and optional parmesan cheese, placing them in separate bowls for easy layering.

Once the crust is blind-baked and slightly cooled, layer one-third of the drained tomatoes in the crust, followed by a mix of the grated cheeses and some fresh basil leaves. Repeat this layering process two more times, finishing with the last layer of tomatoes on top. Spread a mixture of the remaining cheeses and mayonnaise over the top layer.

Reduce the oven temperature to 350°F and place your assembled Southern Tomato Pie back in the oven. Bake uncovered for 30-35 minutes, until the cheese is bubbly and the top is golden-brown.

Once fully baked, carefully remove the pie from the oven and let it cool for about 15 minutes. Cut into wedges and serve warm or at room temperature.