HEAT oven to 350ºF. Crumble mincemeat into medium saucepan; add water. Bring to a boil over high heat. Cook and stir 1 minute. Cool completely.

STIR together flour, salt and walnuts in medium bowl; set aside.

BEAT butter in large bowl with mixer on high speed until fluffy. Gradually blend in 1/3 cup sweetened condensed milk. Beat in flour mixture until mixture resembles coarse crumbs. Press onto bottom of ungreased 13 x 9-inch baking pan to form a crust. Top with mincemeat, spreading evenly.

BEAT cream cheese in medium bowl with mixer until fluffy. Gradually beat in remaining sweetened condensed milk, eggs and vanilla. Carefully pour over mincemeat. Top evenly with walnut halves.

BAKE 30 minutes or until top is set. Cool 30 minutes. Cover and chill. Remove from refrigerator 15 minutes before serving.