Combine the whiskey, Fernet Branca, Simple Syrup and bitters in a glass with ice. Stir the mixture 15 times in a circular motion. Strain into 4 chilled cocktail glasses. Garnish with the orange peels.
Combine the sugar and 1 cup water in a small saucepan and bring to a boil. Cook, stirring, until the sugar dissolves. Remove from the heat and let cool completely. Keep covered in the refrigerator up to 1 month.