In a cocktail shaker, combine the pisco, lime juice, rose-petal jam, bitters and egg white. Dry-shake to emulsify the egg white. Fill the cocktail shaker with ice and shake well, then strain into a chilled coupe. Add the Champagne to the shaker, swirl to rinse, then strain it onto the top of the cocktail. Garnish with the grated cinnamon and the dried rose petal.