Set out 8 tall glasses and place two scoops of lime sherbet in the bottom of each.

Pour the chilled soda slowly down the inside of the glass, letting the foam rise gradually instead of dumping it over the scoops.

Pause once the foam nears the rim and let it settle for about 30 seconds before topping off the glass.

Finish each float with a swirl of whipped cream, if using, and a maraschino cherry on top.

Add a long spoon and a striped straw and serve immediately, before the sherbet melts into the soda.