Pour the chilled cola into a large mixing bowl, watching it fizz and bubble as you transfer it.
Add the sweetened condensed milk to the cola in the bowl.
Whisk the mixture thoroughly until the soda is fully incorporated and the mixture is smooth and slightly frothy.
Transfer the mixture to a freezer-safe container, spreading it into an even layer.
Cover the container with a lid or plastic wrap and place it in the freezer.
Freeze the mixture for at least 4 hours, or until it is firm and scoopable, stirring once or twice to prevent ice crystals from forming.
Once frozen to the desired consistency, scoop the frosty cola mixture into bowls and serve immediately.
