Place potatoes on oven rack or a baking sheet coated with cooking spray.
Bake at 350 for 50 minutes or until tender. Cool. Peel potatoes and mash. Stir in syrup,1 tablespoon brown sugar, and salt.
Preheat broiler.
Spread potato mixture into an 11- x 7-inch baking dish coated with cooking spray. In a small bowl combine walnuts, 1 tablespoon brown sugar, and butter.
Sprinkle walnut mixture over potatoes; broil 2 to 4 minutes or until nuts are lightly browned.