Remove the chilled glasses from the freezer and place them on a stable surface.
Add one generous scoop (about 1/2 cup) of vanilla ice cream to each glass, placing it gently against the side.
Tilt each glass at a 45-degree angle and slowly pour the root beer down the side of the glass to minimize foam overflow.
Continue pouring until the foam rises to about 1 inch from the rim, then wait a moment for it to settle.
Add another small scoop of ice cream on top if desired, then top with whipped cream and a cherry.
Serve immediately with a long spoon and straw, encouraging everyone to enjoy the creamy foam first.