Prepare tart shells: In an electric mixer, cream together butter and sugar until light and fluffy. Add egg and salt, and beat until combined. Add flour all at once, and slowly mix just until flour is evenly moistened. You don't want to mix until a ball forms around the beaters.
Transfer to a plastic bag and form into a 6 inch log. Seal bag, pressing out any air, and refrigerate a minimum of 4 hours or as long as 4 days.
Divide log into 8 parts. On a lightly floured board, roll dough into rounds to fit 8 individual tart pans, 3 inch round x 1 inch deep. The dough should be about 1/8 inch thick. Chill tart shells for 1/2 hour.
Heat oven to 350 degrees F. Line tart shells with parchment paper and fill with pie weights or dry beans. Bake 10 minutes, remove foil and weights and bake shells 5 minutes longer. Remove and cool.
Prepare tart filling: In a large bowl, whisk together the sugar, corn syrup, eggs, butter and orange zest. Divide walnuts and cranberries evenly among the partially baked tart shells. Pour sugar mixture over walnuts and cranberries.
Bake tarts 20 to 25 minutes or until crusts are golden. The edge of the filling will be firmer than the center. Cool tarts of wire racks and refrigerate until ready to serve. Remove cooled tarts from pans and serve.
c.1996, M.S. Milliken & S. Feniger, all rights reserved