HEAT oven to 450°F.
COMBINE flour, salt, ginger and mace in large bowl. Cut in shortening with pastry blender or 2 knives until mixture resembles coarse crumbs. Add water a little at a time, mixing with fork until flour is moistened. Form dough into a ball.
TURN onto lightly floured surface. Flatten and roll dough to form 12-inch circle. Fit into 9-inch pie plate. Trim pastry 1/2 inch beyond edge of pie plate. Fold under extra pastry to build up edge. Flute. Prick bottom and sides of pastry with fork.
BAKE 10 to 12 minutes or until browned. Cool.
COMBINE sugar, cornstarch and gelatin in medium saucepan.
BEAT egg yolks and milk with a wire whisk, stir into gelatin mixture. Let stand 1 minute to soften gelatin. Cook over medium-low heat until mixure thickens and boils; about 8 minutes, stirring constantly. Boil 1 minute.
REMOVE from heat. Stir in butter. Gradually add lemon juice; blend throughly. Pour mixture into large bowl; refrigerate 45 minutes or until mixture mounds when dropped from a spoon. Fold in yogurt.
SPREAD hot fudge topping over bottom of pie crust. Sprinkle with pecans, pressing firmly into sauce. Pour cooled lemon filling over fudge layer. Refrigerate 4 hours or until firm.
GARNISH with frozen whipped topping and grated lemon peel, if desired.