Preheat your oven to 350°F (175°C) and grease or line your muffin tin.

In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until well combined.

In a separate bowl, combine the crushed pineapple, vegetable oil or melted butter, sugar, vanilla extract, and beaten egg. Stir until well mixed.

Pour the wet mixture into the dry ingredients and fold gently until just combined, avoiding overmixing.

Divide the batter evenly among the muffin cups, filling each about two-thirds full.

Bake in the preheated oven for 20-23 minutes, or until golden brown and a toothpick inserted comes out clean.

Allow the muffins to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.