Add the blackberries to a large cocktail shaker and muddle (using a pestle to press down and half turn), add bourbon, lemon juice, and simple syrup. Fill with ice. Shake well to completely chill the contents. Strain into a rocks glass, or your favorite cocktail glass, filled with ice. Garnish with additional blackberries (if desired) and a sprig of fresh rosemary.
To serve, carefully torch the rosemary (being cautious as it can blow off embers), burning a few of the leaves and stem, it will likely self extinguish and smoke.
Notes
Never discard hot matches, or rosemary that has recently been torched. Allow ample time to completely cool down before tossing into the trash.*Simple syrup is an equal mix of water and sugar, dissolved. It’s best to make some ahead of time (usually about 1/3 cup [79 ml] of each, dissolved over low medium heat) and keep it in the refrigerator to use as needed.