For the Filling
2 cups arborio rice
4 cups fancy zucchini, shredded
3 large eggs
freshly ground black pepper
3 cups ricotta cheese
2 cups scallions , white and green partsonly, chopped
1½ cups Parmigiano-Reggiano, freshly grated
1½ cups half and half
1 egg yolk
For the Crostata Dough
2 cups all-purpose flour
½ cup extra-virgin olive oil
1 teaspoon salt
⅓ cup water
In a large bowl, toss the rice and zucchini until evenly distributed. Let stand 30 minutes.
In a small bowl, whisk the eggs with salt and pepper until blended. Combine the egg mixture, ricotta, scallion and Parmigiano-Reggiano in the bowl of an electric mixer. Add the rice and zucchini and mix at low speed until blended. (Alternatively, the mixture can be beaten by hand with a wooden spoon.) Add the half and half and mix until amalgamated. Season to taste with salt and pepper.
Preheat the oven to 375 degrees. Lightly butter an 18 x 12-inch baking pan with sides about 1/2-inch high.
On a lightly floured surface, roll the dough out to a 22 x 16-inch rectangle. Flour the surface as necessary to prevent the dough from sticking. Fold the dough into quarters, center it over the prepared pan and unfold it. The dough should overlap all the sides by about 2 inches.
Pour the rice mixture into the dough-lined pan and smooth it into an even layer. Fold the overhanging dough over the filling to form a two inch border on all sides. Brush the dough lightly with the egg yolk or olive oil. Bake until the filling is firm in the center and the crust is deep golden brown, about 45 minutes. Cool the crostata about 30 minutes, cut into squares and serve warm.
Process 2 cups of the flour, the oil and salt in a food processor until smooth, scraping down the sides of the work bowl once or twice. With the motor running, pour in enough water to make smooth, very soft dough. Turn the dough out onto a lightly floured surface and knead, adding flour if the dough begins to stick to your hands, until the dough is very smooth and no streaks of flour or oil remain, about 1 minute. Wrap the dough with plastic wrap and let it rest 30 minutes at room temperature or up to one day in the refrigerator. Allow refrigerated dough to stand at room temperature 30 minutes before continuing.
Alternatively, pile the flour on your work surface and make a well in the center. Add the olive oil, 1/3 cup water, and the salt to the well. Mix the dough according to the instructions for making pasta dough by hand.