1) Preheat the oven to 400°F.
2) To prepare the vegetables: Slice the tomatoes and squash into 1/2" slices. Cut the pepper into 1" squares.
3) Pour a thin coat of olive oil into two large (cookie-sheet size) rimmed pans. Put the vegetables in the pans in a single layer. Bake for 1 hour, using a spatula to turn vegetables halfway through the bake time.
4) Remove the pans from oven and consolidate the vegetables onto one pan (they will have shrunk considerably, and become soft and golden brown). Remove the pan from the oven, and set it aside while you make the crust.
5) To make the crust: Mix together the flour, semolina, herbs, salt, yeast, olive oil, and enough of the water to form a stiff dough.
6) Turn the dough onto a lightly floured work surface and knead until smooth and elastic, about 10 minutes. Place the dough in a well-greased bowl, turning to coat all sides, cover, and set aside to rise until doubled in bulk, about 1 to 1 1/2 hours. While the dough is rising, make the cheese filling.
7) For the filling: Mix together the cheeses, eggs, and salt. Set aside.
8) To assemble and bake the pie: Divide the dough in half. Roll one piece into a round approximately 16" in diameter. Place the dough on a large baking sheet, into a deep-dish pizza pan or, if you're using a baking stone, onto a sheet of parchment paper.
9) Top the dough with the cheese filling and vegetables, leaving the outside edges uncovered.
10) Roll the second piece of dough into a 16" round, and place it gently atop the vegetables. Use your fingers to seal the two pieces of dough together all around the edge.
11) Brush the crust with olive oil, then set the pie aside to rest for 20 minutes, while you preheat the oven to 425°F (with a baking stone inside, if you have one).
12) Use a peel to slide the pie onto the baking stone, or place the pan on a lower rack. Bake the pie for 30 minutes, or until it's golden brown. Remove it from the oven, and cool it slightly before cutting.
Yield: 8 generous or 12 medium servings.