Chill your serving glass in advance to keep the cocktail chilled longer.
Add 1 ounce rye whiskey, 1 ounce cognac, ¾ ounce sweet vermouth, ¼ ounce Bénédictine , 3 dashes Angostura Bitters, and 3 dashes Peychaud's Bitters to a bar pitcher and add ice. Stir until the ingredients are chilled. Strain into the chilled glass and garnish with a slice of orange peel.
Video
Notes
Alternatively, if you want to keep the drink chilled longer, add a large craft ice cube which inhibits fast melt and keeps the drink cold. I've shown it both ways here.