Chill your glass: Fill a rocks glass with ice and let it sit for a few minutes, then discard the water. Alternatively, you can pre-chill the glass by swirling a bit of ice water around it and then drying it off with a bar towel.
Combine the ingredients: Add the bourbon, Campari, and sweet vermouth to a mixing glass filled with ice. Stir for about 20 seconds until the mixture is well-chilled and diluted.
Strain: Strain the cocktail into the chilled rocks glass over fresh ice.
Garnish: Express the oils from an orange twist over the surface of the drink and then drop it in or use it to rim the glass.
Adjust the sweetness:If you prefer a less sweet cocktail, you can use dry vermouth instead of sweet vermouth. You can also adjust the amount of vermouth to your taste.
Get creative with the garnish:While an orange twist is the classic garnish, you can also experiment with other options like a lemon twist, grapefruit peel, or a Luxardo maraschino cherry.
Batch it up: If you're making cocktails for a crowd, you can easily batch up a Boulevardier. Simply combine all of the ingredients in a pitcher and stir well. Serve it over ice in individual glasses.