Regan's No. 6 Orange Bitters (29.6cl, 45%)

Regan's No. 6 Orange Bitters was created by cocktail historian Gary 'Gaz' Regan, who partnered with the Sazerac Company after five failed attempts to find an orange bitters to his taste; released commercially in 2005, it became a standard-bearer in the category. The bottle label was designed by Ted 'Dr. Cocktail' Haigh. The bitters are built around bitter Seville orange peel, layered with cardamom, coriander and caraway, underscored by cinchona bark, quassia and gentian root, giving a spicier, drier profile than many competing orange bitters. Essential behind professional and home bars, it is a staple for Old Fashioneds, Manhattans, Martinis and Negronis.