COMBINE graham cracker crumbs, sugar and butter in small bowl; press onto bottom of 9-inch springform pan.
BEAT cream cheese until fluffy in large bowl. Gradually beat in sweetened condensed milk until smooth.
SPRINKLE gelatin over lemon juice in small saucepan; let stand 1 minute. Stir over low heat until gelatin dissolves. Add to cream cheese mixture with mincemeat, walnuts and lemon peel; mix well. Fold in whipped cream; pour into prepared pan.
CHILL 4 hours or until set. Garnish with sour cream and additional walnuts, if desired.