The manufacturers of the Original Slush Mug say you can make a commercial quality slushie-style drink in about 10 minutes with the mug, without blenders or ice. The mug has two parts: a 12-ounce capacity insert, called the "Glaciercore," that contains a freezable refrigerant, and an outer insulated plastic handled cup. Once you've frozen the Glaciercore, liquid placed in the insert congeals into an icy slush. You can make many drink variations with juice, coffee, milk, cider and soda, though beverages like diet soda that contain artificial sweeteners cannot be used in the mug.
Remove the Glaciercore insert from the outer plastic mug. Wash the insert. Dry thoroughly inside and out.
Check that your freezer is set at minus 10 degrees Fahrenheit. Place the insert into the freezer six to 12 hours before you plan to use it.
Mix your choice of liquid beverage ingredients in a bowl or large measuring cup. Add no more than 11 total ounces of liquid. Use any combination of milk, tea, coffee, espresso, soda, punch or juice.
Add natural flavorings, if desired. Choose from sugar, citrus fruit zest, pureed fruit, extracts such as vanilla or peppermint, or syrups like chocolate or strawberry syrup. Ensure that the total amount of liquid and added flavorings you put into the Glaciercore insert is less than 11 ounces. Mix the beverage ingredients thoroughly.
Remove the insert from the freezer. Put it into the Slush Mug's outer plastic mug.
Pour the beverage ingredients into the insert. Allow 1 inch of head space at the top.
Use a spoon to scrape off the slush that forms on the inside walls of the Glaciercore insert, stirring it into the rest of the beverage ingredients. Repeat until the drink has reached your desired consistency.
Eat the slushee out of the Slush Mug or transfer it to a separate bowl or glass. Garnish with a sprig of mint or basil if desired. Remove the insert from the outer plastic mug. Wash and dry both items and return the insert to the freezer.
If you've had the Glaciercore insert in the freezer for six hours and it still isn't ready when you gently squeeze it, the insert will feel soft. Check your freezer's temperature and allow the insert to continue freezing until it feels hard to the touch.
Use chilled liquids in your Slush Mug when possible. Room temperature liquids still work, but the process takes longer.
Beverages prepared correctly in the Slush Mug should stay icy for up to two hours.
Do not wash the Glaciercore insert of the Slush Mug in the dishwasher.
Do not use a broken or damaged Glaciercore insert.