Yield: One 9-inch pie.
for the crust
2 1/4 cups all-purpose flour, plus more for dusting
1/2 cup finely grated Parmesan cheese
1 teaspoon coarse salt
3/4 cup (1 1/2 sticks) cold unsalted butter, cut into pieces
1 large egg yolk, plus 1 large egg yolk, for egg wash
1/4 to ˙1/2 cup ice water
1 tablespoon heavy cream, for egg wash
for the filling
2 tablespoons extra-virgin olive oil
1 shallot, finely chopped
1 small zucchini, halved lengthwise and cut crosswise into ˙1/2-inch-thick half-moons
1 1/2 pounds cherry tomatoes
1/2 cup grated Parmesan cheese
4 ounces bocconcini (fresh mozzarella balls) or fresh mozzarella (1-inch pieces)
3 tablespoons fresh basil leaves, chopped
1/4 cup plus 2 tablespoons all-purpose flour
Coarse salt and freshly ground pepper
Make the crust: Pulse flour, cheese, salt, and butter in a food processor until mixture resembles coarse meal. Add 1 egg yolk; pulse to combine. Drizzle in ¼ cup ice water, and pulse until dough just comes together. (If dough is still crumbly, add up to ¼ cup more water, 1 tablespoon at a time.) Form dough into a disk, and wrap in plastic. Refrigerate or freeze until firm, about 30 minutes.
Make the filling: Heat 1 tablespoon oil in a skillet over medium. Add shallot; cook, stirring occasionally, until softened, about 3 minutes. Add zucchini; cook, stirring occasionally, until light golden and liquid has been released, about 5 minutes. Transfer to a large bowl.
Halve one-third of the tomatoes. Stir halved and whole tomatoes, both cheeses, basil, and flour into shallot-zucchini mixture. Season with salt and pepper.
On a lightly floured surface, roll out dough to a 13-inch round, about ¼ inch thick. Make seven 3-inch-long cuts around edge of dough, evenly spaced. Transfer to a 9-inch pie plate. Drizzle shell with remaining tablespoon oil. Transfer filling to shell. Fold in flaps of dough, slightly overlapping. Refrigerate until dough is firm, about 30 minutes.
Preheat oven to 375°F. Whisk cream and remaining egg yolk in a small bowl, and brush over crust. Bake pie on a parchment-lined rimmed baking sheet until crust is golden brown and juices are bubbling, 70 to 80 minutes. Transfer to a wire rack to cool slightly. Serve warm.
I do not have a food processor so I made the crust in a bowl using a pastry cutter.
My cookbook recipe instructs the pie to be baked 70-80 minutes which is how long I baked mine. I notice the online recipe suggests baking 45 minutes. That is a big difference in baking times so use your judgement.