In its simplest form, a snowball cocktail is just advocaat and lemonade. Advocaat -- also known as Dutch eggnog -- is basically a brandy-based custard. It adds a creamy texture and rich flavor to this sweet cocktail. A few commercial advocaats are readily available in liquor stores, or you can make your own. Of course, there are ways to personalize and add depth of flavor to the classic snowball preparation, so try different approaches to find your favorite.
Put a handful of ice cubes into a cocktail shaker. Pour in two to three shots of advocaat per glass, depending on the desired strength and creaminess you want for the cocktail.
Add a squeeze of fresh lime juice into the shaker per serving. Or, for a sweeter preparation, use a splash of lime cordial instead.
Pour other desired ingredients into the cocktail shaker. Two tasty complementary options include 1/2 shot of cognac or sherry per serving. To get away from the more traditional preparation, you could experiment with a few drops of something like a raspberry, blackberry or strawberry liqueur -- but go light, so your cocktail doesn't end up overpoweringly sweet.
Shake the mixture vigorously but briefly. You don't want the ice to start melting and diluting the advocaat. Pour it through the strainer into a highball or Collins glass.
Fill the glass the rest of the way with cold lemonade and stir the drink well. Top it off with a few cocktail cherries if you like.