Ok. We cannot really pass these off as healthy. They practically qualify as a dessert, but they are yummy.
Preheat oven to 350F. Roast potatoes on rimmed baking sheet until tender, 1 to 1 ½ hours. Cool slightly. Scoop flesh into large bowl; discard skins. Mash hot potatoes until coarse puree forms.
Heat cream and butter in small heavy saucepan over low heat until butter melts, stirring occasionally. Gradually stir hot cream mixture into hot potatoes. Stir in syrup, bourbon and spices. Season with salt and pepper.
DO AHEAD: Can be prepared 1 day ahead. Cover and chill. Rewarm in microwave. Sprinkle with nuts and serve.