2 oz Rye
3⁄4 oz Dry vermouth
2 t Amer Picon
1 Maraschino cherry (as garnish)
Stir, strain, straight up, cocktail glass, garnish
Use high quality rye.
The earliest recipe I can find is the 1914 book "Drinks", by Jacques Straub, which quotes the drink as 3/4 oz each good rye and dry vermouth, then 1 dash each Maraschino and Amer Picon. This isTed Haigh's version, which is is excellent.
Vintage Spirits and Forgotten Cocktails, pg. 82
Rye, Dry vermouth, Maraschino Liqueur, Amer Picon, Maraschino cherry