This recipe is on the back of the small Sweet White Rice Flour bag from BRM. It is very good. And pretty easy. We got good results with about the same amount of effort as baking brownies.
My only real points of comparison for butter mochi are what we get from the Hawaiian place down the street, and what we had when we were in Hawaii. This seems pretty authentic. It looks and tastes just like the stuff from down the street, and it has that weird mealy/grainy dissolving in your mouth thing going on.
This recipe will change your life. 🍪