Add loose scoops of vanilla ice cream to a tall serving glass.
Slowly pour the root beer over the ice cream, allowing time for the foam to rise as you pour.
Top with whipped cream and a maraschino cherry if desired. Serve immediately.
Notes
Choose quality ingredients: With only two main ingredients, the flavor of both the ice cream and root beer will be noticeable in the finished float.
Pour in stages: If the foam rises too quickly, pause briefly before adding more root beer to prevent spills.
Customize the flavors: Substitute your favorite soda and ice cream flavors to create different float combinations.
Serve immediately: Ice cream floats are best enjoyed as soon as they are assembled while the soda is still fizzy and the ice cream is holding its shape.