1 cup ice cubes, or as needed
2 lemon slices, divided
2 tablespoons frozen lemonade concentrate
2 tablespoons limoncello liqueur
4 fluid ounces club soda, or as needed
Fill a tall glass with ice cubes. Place 1 lemon slice in the glass. Spoon lemonade concentrate into glass and pour in limoncello. Pour in enough club soda to fill glass; stir well. Place the second lemon slice on the rim of the glass for garnish.