Preparation Preheat oven to 350°F. Combine flour, 1/2 cup sugar, 1 teaspoon orange peel, salt, and baking powder in food processor. Add butter and blend until coarse meal forms. Add 2 eggs and blend until moist clumps form. Turn out dough onto lightly floured surface and knead to combine well, about 1 minute. Divide into 2 pieces, one slightly larger. Wrap and chill smaller piece. Press larger piece over bottom and up sides of 9-inch-diameter tart pan with removable bottom. Using electric mixer, beat ricotta cheese, cream cheese, cornstarch, and vanilla in large bowl to blend. Beat in remaining 1/2 cup sugar, 1 1/2 teaspoons orange peel, and 2 eggs. Transfer filling to dough-lined tart pan. Roll out chilled dough piece to 10-inch round. Place round over tart; trim excess dough. Press edges of tart to seal. Cut 4 slits in top of tart. Bake tart until golden and puffed, about 1 hour. Cool completely.
Preparation Preheat oven to 350°F. Combine flour, 1/2 cup sugar, 1 teaspoon orange peel, salt, and baking powder in food processor. Add butter and blend until coarse meal forms. Add 2 eggs and blend until moist clumps form. Turn out dough onto lightly floured surface and knead to combine well, about 1 minute. Divide into 2 pieces, one slightly larger. Wrap and chill smaller piece. Press larger piece over bottom and up sides of 9-inch-diameter tart pan with removable bottom. Using electric mixer, beat ricotta cheese, cream cheese, cornstarch, and vanilla in large bowl to blend. Beat in remaining 1/2 cup sugar, 1 1/2 teaspoons orange peel, and 2 eggs. Transfer filling to dough-lined tart pan. Roll out chilled dough piece to 10-inch round. Place round over tart; trim excess dough. Press edges of tart to seal. Cut 4 slits in top of tart. Bake tart until golden and puffed, about 1 hour. Cool completely.