A whiskey cocktail with an optional egg white.
Try this one with and without an egg white. For some, consuming an egg white might not be an option.
Put everything except the bitters into a shaker, toss in some ice, and shake this vigorously. Strain the contents into a couple cocktail glass.
The cocktail will be very frothy if you included the egg white in the shaker.
Add those 2 dashes of Angostura bitters as garnish on top of the froth.