You have to stir it around as it freezes, so that it doesn't become one big lump, like a custard ice-cube. So just combine your freezing spell with whatever spell you use to stir milk into your tea or whatever, and keep it going for a while. That should work. I might try one myself. I could make coffee icecream.
I'm going to have slices of lots of different types of pie, because I like all kinds of pie. I hope there's pecan pie, and cherry pie, and apple pie at least.