4 cups vanilla ice cream
3 cups cornflakes cereal, crushed
1/4 cup lightly packed light brown sugar
2 tsp ground cinnamon
1/4 tsp ground nutmeg
pinch fine salt
1/2 cup unsalted butter
1 tsp vanilla extract
Chocolate sauce and whipped cream, for serving (optional)
Arrange a rack in the middle of the oven and heat the oven to 350F/175C. Meanwhile, line 2 baking sheets with parchment paper. Scoop the 4 cups of vanilla ice cream into 8 balls (about 1/2 cup each) onto 1 of the prepared baking sheets. Freeze until firm, about 1 hour. Make the coating while the ice cream freezes.
Crush the 3 cups cornflakes into crumbs. Place in a large bowl, add the brown sugar, cinnamon, nutmeg, and salt, and stir until well combined. Melt butter. Add the butter and vanilla extract to the cereal mixture and toss to coat evenly. Transfer to the second baking sheet and spread into an even layer. Bake, stirring occasionally, until golden brown, about 10 minutes. Let cool completely, then transfer to a clean bowl.
Roll the ice cream balls in the cereal mixture to coat, then place back on the baking sheet. Freeze at least 30 minutes before serving with whipped cream and a drizzle of chocolate sauce if desired.