For shortbread base, preheat oven to 350°F (180°C) and line an 8-inch (20 cm) square pan with parchment paper so that it hangs over the sides of the pan. Combine flour and sugar and cut in butter until it’s a rough, crumbly texture. Press crumble into prepared pan and bake for 15 minutes or until golden brown around the edges. Cool completely.
For filling, beat eggs by hand with brown sugar. Stir in pineapple, coconut, candied pineapple, vanilla, flour and baking powder and spread over cooled base. Bake for about 25 minutes, until it’s an even golden brown color. Cool.
For icing, beat all ingredients together until smooth and spread over cooled pineapple layer. Let set before slicing into squares or bars.