Preheat the oven to 210°C (410°F) and line a 12-hole muffin pan with muffin liners and set aside.
Strain the juice from the crushed pineapple into a cup. Depending on each tin of pineapple will depend on how much juice you will get from the tin. If there is less than 1 cup of juice top up the cup with water.
In a large bowl, cream the butter and sugar until light.
Add in the eggs and vanilla extract and beat until light and fluffy.
Add in the crushed pineapple and pineapple juice and beat that through.
Sift in the flour, baking powder and salt and fold that through the wet ingredients until just combined. Don't over work the mixture.
Spoon the muffin mixture into each muffin well. They should be ¾ full. Place in the oven to bake.
Bake for 5 minutes before turning down the heat to 180°C (350°F) to bake for a further 15-20 minutes. A skewer inserted in the middle should come out clean, they should be lightly golden on top and springy when touched.
After five minutes, remove the muffins from the tray and place on a rack to cool. Serve warm with butter or enjoy cold.