Pour the chilled cola soda into a freezer-safe container and place it in the freezer.
Let the soda freeze for about 3 hours, checking occasionally to ensure it’s not fully solidified, but forming a slushy consistency with icy crystals.
Remove the frozen soda from the freezer and break it into chunks using a spoon or spatula to loosen the icy parts.
Transfer the frozen chunks into a blender.
Blend the mixture on high until it reaches a thick, granular slush with a slightly frothy top, about 20-30 seconds, being careful not to over-process into liquid.
Pour the blended slush into chilled glasses, allowing the icy crystals to spill over slightly for a rustic look.
Serve immediately with a straw or spoon, enjoying the crisp, bubbly texture that offers a nostalgic, refreshing burst with every sip.