Preheat oven to 350°F Line muffin pan with paper liners.
In a small bowl, mix together flour, baking powder and salt.
In a large bowl, whisk together sugar, oil and egg until smooth. Alternately whisk in flour mixture and milk, making three additions of flour mixture and two of milk, beating until smooth. Stir in pineapple.
Scoop batter into prepared pan. Bake in preheated oven for 20 to 25 minutes or until tops of cupcakes spring back when lightly touched. Let cool in pan on rack for 10 minutes. Remove from pan and let cool completely on rack. Top cooled cupcakes with frosting, if desired.