1Heat oven to 350°F. Line 17x12-inch half-sheet pan with foil. Arrange graham crackers in single layer in pan, slightly overlapping.
2In 2-quart saucepan, heat brown sugar and butter to boiling over medium heat, stirring constantly, until smooth. Remove from heat; stir in vanilla. Pour mixture over graham crackers, spreading to coat evenly. Sprinkle with walnuts.
3Bake 15 minutes. Reduce oven temperature to 325°F. Bake 10 minutes longer or until lightly browned and bubbly. Immediately sprinkle with apple chips and salt. Cool completely in pan on cooling rack. Refrigerate 30 minutes or until candy is hardened. Break into pieces. Store tightly covered at room temperature.