Mix all ingredients except passion fruit in a shaker. Fill the shaker with ice and shake. Strain the drink into a glass with crushed ice. Cut a passion fruit in half, scoop out the seeds from one half and mix into the drink. Garnish with orange zest and the other half of the passion fruit.
The simple syrup can be made by combining 3 parts sugar with 2 parts water.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Buffy.