Making frozen cocktails that stay frozen can be a challenge when you don't have access to a professional slushy machine. The key to success is keeping your ingredients as cold as possible while blending.
One way to combat the heat is to batch your drinks in advance and chill the mixture in the freezer. Any freezer-safe container will work as long as it seals tightly. Thanks to alcohol and sweeteners, most cocktails won't freeze solid, even if you keep them in the freezer overnight. But particularly juicy drinks, and any that are lower in alcohol, may become slushy after a couple of hours. Before blending, let the mixture sit at room temperature for a minute or two to make it easier to pour into the blender.
If you find that your ingredients are still too liquidy after blending, you can add extra ice to thicken the mixture. However, adding too much ice will dilute the flavor of your cocktail, so use it sparingly.
To make the process smoother, you can also crush your ice in advance using a meat mallet and a resealable bag wrapped in a kitchen towel. This will save your blender some work, and the less time your drink spends in the blender, the less the machine will heat up.
Here is a recipe for a frozen Moscow Mule that you can try:
Ingredients:
1/4 cup (packed) light or dark muscovado sugar or dark brown sugar
2 1/2 teaspoons finely grated peeled ginger
4 oz. vodka
3 oz. fresh lime juice
Pinch of kosher salt
2 lime wheels
2 cups ice
Special equipment:
A 1-pint glass jar
2 glass smoothie cups with straw
Instructions:
In a 1-pint glass jar, stir together the muscovado sugar, ginger, and 1/4 cup of boiling water until the sugar is dissolved.
Let the mixture cool slightly, then add the vodka, lime juice, and salt. Seal the jar and shake to combine.
Freeze the mixture until ice-cold but not solid, for at least 1 hour and up to 4 hours.
When ready to serve, transfer the mixture to a blender and add 2 cups of ice.
Puree on high speed until thick and smooth. If needed, you can add a few more ice cubes to thicken the mixture, but keep in mind that the more ice you add, the more diluted the drink will be.
Divide the cocktail between 2 highball glasses and garnish each with a lime wheel and a straw.
By following these steps, you can make a delicious and refreshing frozen cocktail that stays frozen even in hot weather.