What ingredient is not used in a Peppermint Patty cocktail?

In a traditional Peppermint Patty cocktail, the typical ingredients include white crème de menthe, dark crème de cacao, and a cream or dairy component to create a rich, smooth texture. The purpose of using white crème de menthe is to provide that distinct peppermint flavor, while dark crème de cacao adds a chocolatey richness that complements the other flavors, resulting in a creamy and flavorful drink.

Baileys, while a creamy liqueur, is not a standard ingredient in a Peppermint Patty cocktail. Although it could theoretically be added for an alternative twist, it does not belong to the classic formulation of this drink. The combination of the other ingredients is what defines the Peppermint Patty, and adding Baileys would alter the intended flavor balance and character of the cocktail.