A few of things to keep in mind when freezing milk:
• Allow for expansion: Freeze milk in moisture- and vapor-resistant containers with 1 to 1 1/2 inches of space at the top to prevent bursting.
• Thaw it safely: Place the frozen milk in the refrigerator to thaw. Depending on the size of the container, it may take a day or longer to defrost.
• Shake it up: Freezing may cause the milk to separate and develop a grainy texture. To restore some smoothness, you can stir, shake, or beat it with a hand mixer or immersion blender.
Because of the potential changes in quality and texture, frozen milk is often better for cooking and baking than straight drinking. We like freezing it in ice cube trays, which makes it easier to defrost and use in recipes.