6.75 ounces all-purpose flour (about 1 1/2 cups)
1/2 teaspoon salt
3 tablespoons chilled unsalted butter, cut into small pieces
2 tablespoons vegetable shortening, cut into small pieces
1/4 cup ice water
1 tablespoon extra-virgin olive oil
2 cups (1/8-inch-thick) slices yellow squash
2 cups (1/8-inch-thick) slices zucchini
1/4 cup chopped shallots
1 tablespoon chopped fresh thyme
1 cup 2% reduced-fat milk
3/4 teaspoon salt
1/4 teaspoon freshly ground black pepper
4 slices center-cut bacon, cooked and crumbled
3 large egg whites
3 large eggs
3/4 cup (3 ounces) shredded part-skim mozzarella cheese
To prepare crust, weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine 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 mixture resembles coarse meal. With food processor on, add ice water through 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 chilled dough on plastic wrap. Cover dough with 2 additional sheets of overlapping plastic wrap. Roll dough, still covered, into a 12-inch circle. Place dough in freezer 5 minutes or until plastic wrap can easily be removed. Remove top sheets of plastic wrap, and fit dough, plastic wrap side up, into a 9 1/2-inch deep-dish pie plate coated with cooking spray. Remove remaining plastic wrap from dough. Fold edges under, and flute. Pierce bottom and sides of dough with fork. Bake at 400° for 15 minutes. Cool on a wire rack.
Reduce oven temperature to 350°.
To prepare the filling, heat a large nonstick skillet over medium-high heat. Add oil to pan; swirl to coat. Add squash, zucchini, shallots, and thyme; saute for 5 minutes or until squash and zucchini are tender, stirring frequently. Cool the squash mixture slightly.
Combine 1 cup reduced-fat milk and the next 5 ingredients (through eggs) in a large bowl, stirring with a whisk. Arrange squash mixture evenly over crust, and sprinkle with 3/4 cup mozzarella cheese. Pour the egg mixture over cheese. Bake at 350° for 45 minutes or until filling is set. Cool for 15 minutes on a wire rack.