In a large bowl, combine the flour, sugar, orange peel and salt. Cut in butter until crumbly. Add egg. Gradually add cream, tossing with a fork until a ball forms. Cover and refrigerate for at least 30 minutes or until easy to handle.
On a lightly floured surface, roll out pastry into a 13-in. circle. Press onto the bottom and up the sides of an ungreased 11-in. fluted tart pan with removable bottom.
In a large bowl, combine the filling ingredients. Pour into crust. For topping, combine the flour, sugar, brown sugar, salt and cinnamon. Cut in butter until crumbly. Stir in walnuts and ginger. Sprinkle over filling.
Bake at 350° for 45-55 minutes or until a knife inserted near the center comes out clean. Cool on a wire rack. Refrigerate leftovers. Yield: 14 servings.