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.
Prepare topping: Stir together crushed cornflakes cereal and next 3 ingredients. Sprinkle over sweet potato mixture in diagonal rows 2 inches apart.
Bake at 350° for 30 minutes. Remove from oven; let stand 10 minutes. Sprinkle miniature marshmallows in alternate rows between cornflake mixture, and bake 10 more minutes.
More Irresistible Options
Golden Meringue-Topped Sweet Potato Casserole: Omit Cornflake, Pecan, and Marshmallow Topping. Bake Sweet Potato Filling at 350° for 30 minutes. Remove from oven; let stand 10 minutes. Beat 4 egg whites at high speed with an electric mixer until foamy. Gradually add 1/4 cup granulated sugar, 1 Tbsp. at a time, beating until stiff peaks form and sugar is dissolved. Spread meringue over sweet potato mixture; bake 10 more minutes or until golden. Hands-on Time: 30 min.; Total Time: 2 hr., 40 min.
Per serving: Calories 216; Fat 3.8g (sat 2.1g, mono 1.1g, poly 0.2g); Protein 4.8g; Carb 41.3g; Fiber 3.1g; Chol 31mg; Iron 1mg; Sodium 271mg; Calc 66mg
Pecan-Topped Sweet Potato Casserole: Omit Cornflake, Pecan, and Marshmallow Topping. Pulse 3 Tbsp. all-purpose flour and 1/4 cup firmly packed brown sugar in a food processor until combined. Add 1 Tbsp. cold butter, cut into small pieces, and process 45 seconds or until mixture resembles coarse meal; stir in 1/3 cup 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. Hands-on Time: 20 min.; Total Time: 2 hr., 20 min.
Per serving: Calories 267; Fat 8.8g (sat 3.4g, mono 3.5g, poly 1.4g); Protein 3.7g; Carb 44.5g; Fiber 3.6g; Chol 35mg; Iron 1.4mg; Sodium 256mg; Calc 75mg