Wasei-eigo from English 'soft cream'. Refers specifically to the soft, swirled ice cream dispensed from a machine, not regular scooped ice cream.
wasei-eigo (Japanese-coined English), from soft cream
On a hot day, I crave soft serve ice cream.
The soft serve at this shop is rich and delicious.
It was so hot that the soft-serve melted right away.
This farm sells soft-serve ice cream.
The child is walking along licking a soft-serve ice cream cone.