Stir together bourbon, lemon juice, and powdered sugar in a pitcher until sugar dissolves (about 30 seconds). Cover and chill 3 hours. Divide among 8 Champagne flutes; top each with 1/4 cup chilled hard cider (such as Angry Orchard). Garnish, if desired.
Make-Ahead Tip: Mix together the first 3 ingredients of this twist on a classic French 75 up to 24 hours ahead.