Place bourbon, vermouth, Bénédictine, and bitters in a mixing glass, and stir briefly with ice. Strain into a coupe glass. Garnish with expressed lemon peel, if desired.
Notes
Using a lighter to heat the lemon peel before "expressing" helps yield more essence/juice. Express by rubbing pith side down between thumb and forefinger.
Recipe by Bake from Scratch at https://staging.bakefromscratch.com/the-vow-of-silence/