I haven’t tried these personally, but I’ve heard that they work great for freezing yogurt, or for sending yogurt to school. Or enjoying as an after school snack.
It’s loads cheaper (and healthier) to buy a large container of plain or lightly sweetened yogurt and mix in your own sweetener and fresh fruit. Load them up in the evening, freeze overnight and drop in the lunchbox in the morning. They likely won’t stay completely frozen, but will be the perfect temperature come lunchtime.
Would also be great for making your own parfaits for lunch…something an older kid could do easily! If you have the yogurt in a separate container, then it won’t get the granola soggy!
You can find these on Amazon and other cookware retailers.