Grease and bake potatoes in the skin at 400° for 1 hour. (Be sure to protect your oven from all of the drips.) Cool, take skins off and put in a bowl.
In a large bowl, combine half-and-half, syrup, vanilla, salt, and egg, stirring with a whisk. Add potatoes to egg mixture; beat with a mixer at medium speed until smooth. Spoon potato mixture into a 13" x 9" baking dish coated with cooking spray.
Combine flour and sugar in a food processor (or with a fork); pulse to combine. Add chilled butter; pulse until mixture resembles coarse meal. Stir in pecans; sprinkle over potato mixture.
Cover and bake at 375° for 15 minutes. Uncover and bake an additional 25 minutes or until the topping is browned and the potatoes are thoroughly heated.
*Can make and freeze up to 2 weeks ahead. Thaw in fridge and bake as directed.
*May use canned yams
*Add a pinch of cinnamon and nutmeg if desired
*Can add 1/8 tsp. ground red pepper if you want to add a little heat.