Add cornflakes to a large resealable plastic bag. Seal bag tightly and crush cornflakes with a flat mallet or rolling pin, until you have fine crumbs.
In a large (10-inch) skillet, melt butter over medium-high heat. Once melted, stir in crushed cornflakes and cinnamon. Cook for 3-4 minutes, stirring constantly, until golden brown and fragrant. Pour mixture into a shallow dish and let cool for 15-20 minutes.
Meanwhile, prepare a medium baking sheet. Remove ice cream from freezer. With latex-gloved hands (not necessary, but recommended to avoid super-cold hands, and ice cream that melts too quickly), scoop and shape ice cream into 5 round baseball-sized balls. Place on the baking sheet. Roll balls into cornflake mixture, evenly coating and pressing cornflake mixture around outer surface.
Serve immediately topped with desired toppings. Or, place in freezer on a baking sheet (before adding toppings) and chill until ready to add toppings and serve.