Preheat oven to 400°F.
Prepare potatoes by piercing them with a fork to vent and place them on a parchment or foil-lined baking sheet. Bake for 40-60 minutes until a fork can be easily inserted.
Remove from the oven and adjust temperature to 350°F. Let potatoes cool slightly. When cool enough to handle, remove skins and lightly mash in a medium mixing bowl. Add the Challenge Butter, eggs, brown sugar, vanilla, milk, cinnamon and salt. Use a hand mixer to whip sweet potato mixture until it becomes smooth, light and creamy, about 4-5 minutes on high. Pour the mixture into a greased 2 ½ quart baking dish.
Make the Butter Pecan Topping by combining pecans, brown sugar, flour, butter, salt and baking powder in a medium bowl with a pastry blender or spoon until the mixture is well incorporated. Sprinkle topping mixture onto the potato souffle.
Bake for 35-50 minutes or until the top is golden brown and bubbling.
Cool slightly and serve.
To make ahead, make the soufflé portion (steps 1-3) as directed in the recipe. Do not bake the soufflé. Place the soufflé mixture in a freezer-friendly bag or container. It can be safely frozen or refrigerated for 3 days. Don’t make the Butter Pecan Topping until the day you serve the soufflé. If frozen, remove the casserole and place it in the refrigerator to thaw the night before you plan to serve it. On day of serving, remove the thawed casserole from the refrigerator an hour before baking. Make the Butter Pecan Topping and sprinkle it on the soufflé. Follow baking instructions.