The Prince Edward is a great example of the power of bitters to completely change the character of a drink. The PDT cocktail book tells us that the original recipe had no bitters, making it a sort of wet Rusty Nail.
The addition of a couple good shakes of orange bitters transforms the drink, sharpening the edges of what was otherwise a plain Scotch cocktail. For maximum flavor, we like to use a combo of complex, spicy Regan’s Orange Bitters No. 6 and the comparatively simpler and sweeter Fee’s Orange Bitters.
Stir with ice and strain into a chilled cocktail or coupe glass. Garnish with a twist of orange or lime.