For the cake

1. Preheat oven to 180C.
2. In a large bowl, beat the sugar and butter until creamy and pale. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed. Add vanilla and mix to combine.
3. Combine milk and vinegar in a small bowl. Set aside. 
4. Add the flour alternately with milk to the butter mixture, beginning and ending with the flour. Scrape down the mixing bowl with a spatula and turn the batter over several times to ensure all of the ingredients are well incorporated. Beat just until incorporated.
5. Bake for 20 – 25 minutes, or until a skewer comes out clean when poked in the center.

For the icing

1. Add softened butter and vanilla to the mixing bowl and mix until completely combined.
2. Add sugar and beat on low until it is incorporated. Then move mixer up to medium-high speed. Scrape sides and bottom of bowl often. When completely mixed the frosting may appear dry.
3. Add milk a little bit at a time until frosting is the proper consistency.
4. Add in your passionfruit curd.
5. Decorate your cake as you like!!