Combine all ingredients in a cocktail shaker with ice and a shake until chilled.
Strain into a rocks glass filled with ice.
Alternatively, you could combine the ingredients in the glass, and layer the cream on top, then stir to combine.
Notes
The White Russian is a difficult cocktail to mess up, so feel free to change the ingredient ratios. In 3-Ingredient Cocktails, Robert Simonson opts for 1½ ounces of vodka, ¾ ounce of Kahlúa, and ¾ ounce of heavy cream.