In a cocktail shaker filled with ice, combine pisco, lime juice, simple syrup and egg white.
Shake well for 2-3 minutes to invigorate the egg white. If you don't shake it enough, you won't have a very thick layer of froth on top.
Strain into a Nick & Nora glass or other cocktail glass.
Carefully place four drops of Angostura bitters on top of the foam.
Draw the tip of a cocktail pick or toothpick through the center of the drops to make them into heart shapes.
Notes
Egg whites: Consuming raw or lightly-cooked eggs poses a risk for food-borne illness. Omit the egg whites or use aquafaba if you don't want to use egg whites. If using eggs, you can use one egg white for two drinks if you are using large eggs or bigger. If you prefer, prepare this cocktail with a dry shake first. Then add the ice and do a second shake. This can help make the egg white foam extra foamy!Lime juice: Fresh squeezed lime juice is the best option for this cocktail! You can use bottled if you're in a pinch, but the flavor is better with fresh lime juice. Substitutions: You can use 2 ounces of sour mix place of the lime juice and simple syrup.