How do you stop mixins from being pulled to the top?

I always seem to have this problem. I make low calorie ice cream, and I mix it once on light ice cream, then I resent it till it's Not snowy or chunky, then I dig down to the bottom and put my mixins in.

I just had a Captain Crunch cereal milk one, and the 40 g of cereal I put in all got pulled up to the top 1/3 of the ice cream.