In a mixing bowl, combine the flour and salt. This helps to evenly distribute the salt throughout the flour.

Add the cold, cubed butter to the flour mixture. Using a pastry cutter or your fingers, work the butter into the flour until the mixture resembles coarse crumbs. This step is crucial for a flaky crust.

Gradually add the ice water, one tablespoon at a time, mixing until the dough comes together. You may need a little more water, but avoid overworking the dough.

Form the dough into a disk, wrap it in plastic wrap, and refrigerate for at least 30 minutes. Chilling the dough helps to relax the gluten, making it easier to roll out.

While the dough is chilling, prepare the filling. Slice the tomatoes and place them in a colander to drain excess moisture. This prevents a soggy pie.

In a mixing bowl, combine the mozzarella cheese, ricotta cheese, basil, parsley, oregano, salt, and pepper. Mix well to ensure even distribution of flavors.

Preheat your oven to 375°F (190°C). This ensures the pie bakes evenly.

On a lightly floured surface, roll out the chilled dough into a 12-inch circle. Carefully transfer it to the pie dish, pressing it gently into the bottom and sides.

Spread half of the cheese mixture on the bottom of the crust, then layer half of the sliced tomatoes on top. Repeat with the remaining cheese and tomatoes.

Brush the edges of the crust with the beaten egg to give it a golden color when baked.

Place the pie on a baking sheet to catch any drips and bake in the preheated oven for 40-45 minutes, or until the crust is golden brown and the filling is bubbly.

Remove the pie from the oven and allow it to cool for at least 10 minutes before slicing. This helps the filling set, making it easier to cut.