2 oz. Maker's Mark bourbon
1 oz. Martini Rosso vermouth
2 dashed bitters (Angostura is the classic, I prefer Fee Brother's Old Fashioned)
Place a Marachino cherry and a couple drops of Marachino liquid in a well-chilled martini glass. Shake the liquors vigorously with ice and strain into glass.
I find the best variation on the Manhattan Cocktail come from altering the vermouth (substituting Punt e Mes or Carpano Antico Formula), bitters, or fruit (orange peel, burnt or not). For the bourbon, old standards work better than small batch.