Posthumus's Jaws inspired 'Killer Cocktail' impressed the judges, which included journalists and bar experts.
Posthumus is to be rewarded with a trip to Italy for the Venice Film Festival, where she will have the opportunity to serve her Disaronno signature cocktail to celebrities.
The competition, now in its third year, started with castings which attracted over 1000 applicants. These were held in locations inspired by movie sets all over the world, including Italy, Germany, France, Spain, Belgium, Russia, Australia, US and Canada.
This year, as part of its film theme, participants took part in acting master classes, where they were offered tips on how best to show off their talents.
Cocktail: Killer Cocktail
45 ml Disaronno
30 ml gin: Beefeater
30 ml fresh lemon juice
10 ml Campari
10 ml passion fruit syrup: Monin
3 Dashes cranberry bitters Fee Brothers
Garnish: lemon zest
Shake all the ingredients with cubed ice, except for the bitters and zest. Strain over crushed ice into a pre-chilled shark-mug. Add 3 dashes of the cranberry bitters on top (bramble-style) to make it look like a bloody float, add a short straw and the lemon zest, cut into a shark fin.