Place a cherry in each of eight 6- to 7-ounce molds or paper cups. Fill halfway with root beer. Tilt to get the angled design and freeze until almost firm, 1 to 2 hours.
Add ice cream and insert sticks. Cover and freeze for 1 hour. Slowly add more root beer, skimming off any foam, until the molds are full. Cover; freeze for at least 6 hours, or until firm.
Remove from freezer. Let stand at room temperature for about 5 minutes before unmolding.
Recipe adapted from Pops! Icy Treats for Everyone copyright © 2008 by Krystina Castella. Photographs copyright © 2008 by Emily Brooke Sandor. Reprinted with permission of Quirk Books; quirkbooks.com.