HEAT oven 425 degrees F. Bake pie crust 6 minutes; remove from oven. Reduce oven temperature to 375 degrees F.
BEAT cream cheese in large bowl until fluffy. Gradually beat in sweetened condensed milk until smooth. Stir in lemon juice. pour into partially baked pie crust.
COMBINE 1 tablespoon brown sugar and cornstarch in small bowl; mix well. Stir in cranberry sauce. Spoon evenly over cream cheese mixture.
COMBINE flour and remaining 2 tablespoons brown sugar in medium bowl; cut in butter with pastry blender or 2 knives until mixture resembles coarse crumbs. Stir in walnuts. Sprinkle evenly over cranberry mixture.
BAKE 45 to 50 minutes or until bubbly and golden. Cool. Serve at room temperature or chill thoroughly.