Yes, and it works well. But milk behaves differently to juice or soda, so it is worth knowing what to expect before you pour.
What actually happens with milk
Juice and soda freeze into small ice crystals, which is what gives you that grainy slush texture. Milk has fat in it, and fat stops those crystals forming properly.
So instead of a slush you get something closer to soft serve. Thicker, creamier, smoother. Plenty of people prefer it.
Use whole milk, not skimmed
Fat is what keeps the texture soft. Whole milk gives you a proper creamy result. Skimmed milk is mostly water, so it freezes harder and you end up fighting the cup.
If skimmed is all you have, add a spoonful of cream or a scoop of ice cream to bring the fat content up.
Chocolate milk is the best version
It has fat from the milk and sugar from the chocolate, and sugar is what stops a drink freezing into a solid block. That combination is close to ideal for this cup.
Plain milk on its own works, but it tastes like frozen milk. Add chocolate, strawberry syrup, a spoon of honey, or a little vanilla and sugar.
We have a full chocolate milk slushy recipe if you want quantities.
Milkshakes work too
Pour a shop bought milkshake straight in. It already has the sugar and fat sorted, so it comes out well every time. Same goes for a milkshake you have blended at home.
Dairy free options
Oat milk works best. It has enough fat and natural sugar to hold a soft texture.
Coconut milk works well and gives a rich result. Use the drinking kind rather than the tinned kind, which is too thick.
Almond milk is the weakest option. It is low in fat and freezes hard. If you use it, pick a sweetened version.
Clean it straight away
This matters more with milk than anything else. Dairy dries into the seal and the straw, and once it does it is hard to shift and it will smell.
Rinse the cup, lid and straw as soon as you finish. Hand wash in cool or warm water, never hot and never a dishwasher, then dry it and put it back in the freezer.
One thing to avoid
Do not use milk that is close to its date. Freezing does not stop milk turning, and a cup that has held old dairy is unpleasant to clean.
