1Heat oven to 400°F. In medium bowl, mix crust ingredients until soft dough forms. Press firmly and evenly against bottom and side of ungreased 9-inch tart pan with removable bottom.
2Bake 10 to 13 minutes or until light golden brown; cool on cooling rack. Reduce oven temperature to 350°F.
3In 2-quart saucepan, melt 2 tablespoons butter over low heat. Stir in condensed milk and chocolate chips. Cook over low heat, stirring occasionally, until chocolate is melted. Stir in vanilla and salt; stir in walnuts. Spread in baked crust.
4Bake about 20 minutes or just until edge is set. Cool in pan on cooling rack, about 1 hour to serve warm, or serve at room temperature. To serve, spoon whipped cream onto center of tart and top with chocolate curls or, top each slice with whipped cream and chocolate curls.