Preheat oven to 180ºC (356ºF) fan-forced.
Lightly grease a 7-inch x 11-inch (17cm x 27cm) rectangle cake tin with butter and line the base with parchment paper. Dust sides with flour, or if you're not using a non-stick tin, line the entire tin with parchment paper. Set aside.
In a large mixing bowl add flour, baking soda and sugar. Whisk until well combined.
In a separate small bowl, whisk the eggs with a fork.
To the flour mixture, add whisked eggs, can of crushed pineapple (plus the juice), and vanilla.
Using a rubber spatula or wooden spoon, fold and mix until incorporated and no visible streaks of flour remain. Do not over-mix.
Pour batter into prepared tin, spreading out evenly with the spatula.
Bake for 22-25 minutes or until a toothpick inserted into the middle comes out clean or with only a few moist crumbs. It will be lightly golden.
Remove from oven and set aside to cool in tin for 10 minutes.
Gently remove from tin and transfer to a wire rack to cool completely.