Preheat the oven to 160°C / 320°F (fan/convection) or 180°C / 355°F (standard). Grease and line a 20 cm (8 inch) round cake tin with baking paper.
In a large mixing bowl, sift together plain flour and baking powder. Whisk in sugar. Make a well in the centre of the dry ingredients.
Add melted butter, milk and vanilla essence. Whisk altogether until well combined (the butter may solidify and make the batter a bit lumpy - this is okay).
Pour into the prepared tin. Bake for 45-50 minutes or until golden and a skewer inserted in the centre of the cake comes out clean.
Allow to cool in the tin for 10 minutes before transferring to a wire rack to cool completely.
