Put the passion fruit puree, rum and Simple Syrup in a cocktail shaker, add large ice cubes, shake vigorously, double-strain into a champagne flute and top with the champagne. Use a bar spoon to slowly pull from the bottom to mix throughout. Garnish with a rose petal.
Combine the sugar and 1 cup water in a small saucepan and bring to a boil. Cook, stirring, until the sugar dissolves. Remove from the heat and let cool completely. Keep covered in the refrigerator up to 1 month.