Heat oven to 350°F. Pierce sweet potatoes all over with fork; place on cookie sheet with sides. Bake 1 hour 15 minutes to 1 hour 30 minutes or until tender when pierced with fork. Let stand 15 minutes or until cool enough to handle.
Meanwhile, in 1-quart saucepan over medium heat, heat butter, brown sugar, milk, corn syrup and cinnamon to boiling, stirring constantly. Boil and stir 1 minute or until slightly thickened. Remove from heat; keep warm.
Peel sweet potatoes; place in large bowl. Mash until no lumps remain. Add cream and salt; mash until smooth. Spoon potatoes into large serving bowl. Serve with brown sugar sauce.