To prepare the crust, lightly spoon the flour into a dry measuring cup; level with a knife. Combine the flour and 1/2 teaspoon salt in a food processor, and pulse 2 times or until combined. Add butter and shortening; pulse 4 times or until the mixture resembles coarse meal. With the ood processor on, add the ice water through the food chute, processing just until the mixture is combined (do not form a ball). Press mixture into a 4 inch circle on plastic wrap, and cover. Refrigerate for 1 hour.
Preheat oven to 400°.
Slightly overlap 2 sheets of plastic wrap on a slightly damp flat surface. Unwrap and place the chilled dough on the plastic wrap. Cover dough with 2 additional sheets of overlapping plastic wrap. Roll dough, still covered, into a 12 inch circle. Place the dough in the freezer 5 minutes or until theplastic wrap can easily be removed. Remove the top sheets of plastic wrap, and fit dough, plastic wrap side up, into a 9 1/2 inch dee-dish pie plate coated with cooking spray. Remove the remaining plastic wrap from the dough. Fold the edges under, and flut. Pierce the bottom and sides of dough with a fork. Bake at 400° for 15 minutes. Cool on a wire rack.
Reduce the oven temperature to 350°.
To prepare the filling, heat a large nonstick skillet over medium-high heat. Add oil to the pan; swirl to coat. Add the squash, zucchini, shallots, and thyme; saute for 4 minutes or until the squash and zuchhini are tender, stirring frequently. Cool the squash mixture slightly.
Combine milk and the next 5 ingredients (through eggs) in a large bowl, stirring with a whisk. Arrange the squash mixture evenly over the crust and sprinkle with 3/4 cup mozzarella cheese. Pour the egg mixture over the cheese.
Bake at 350° for 45 minutes or until the filling is set. Cool for 15 minutes on a wire rack.