No, those two scoops aren't vanilla ice cream. They're butter.
This fish lying on a bed of vegetables was served on a sizzling hot plate. It was topped with two scoops of butter. What you had to do was spread the butter over the fish and then stir and mix everything up.
Grilled, do-it-yourself dishes like this seem quite popular in the places we visited in Hokkaido. All the ingredients were fresh so of course it was delicious!