Prepare filling: Preheat oven to 400°. Bake sweet potatoes on a baking sheet 1 hour or until tender. Reduce oven temperature to 350°. Let potatoes stand until cool to touch (about 20 minutes); peel and mash with a potato masher.
Beat mashed sweet potatoes, 2 Tbsp. softened butter, and next 5 ingredients at medium speed with an electric mixer until smooth. Spoon mixture into an 11- x 7-inch baking dish coated with cooking spray.
Pulse flour and 1/4 cup firmly packed brown sugar in a food processor until combined. Add 1 Tbsp. cold butter, and process 45 seconds or until mixture resembles coarse meal; stir in finely chopped pecans. Sprinkle mixture over Sweet Potato Filling in baking dish.
Bake at 350° for 40 to 45 minutes or until topping is golden brown.