Black Russian

Black Russian
Mix 40% vodka and 60% Kahlua
The Black Russian is a cocktail of vodka and coffee liqueur. It contains two parts vodka to one part coffee liqueur, per IBA specified ingredients. Traditionally, the drink is made by pouring the vodka over ice cubes or cracked ice in an old-fashioned glass, followed by the coffee liqueur.
Source: https://en.wikipedia.org/wiki/Black_Russian