Preheat the oven
to 180.C/350"F/Gas 4. Melt the butter in a 25cm/10in
ovenproof cast-iron frying pan. Then reserve 15ml/l
tbsp butter. Add the brown sugar to the pan and stir
to blend. Place the pineapple on top in one layer.
Set aside.
Whisk together
the egg yolks, reserved butter and lemon rind until
well blended. Set aside.
Beat the egg
whites and salt until stiff. Gradually fold in the
caster sugar, then the egg yolk mixture.
Sift the flour
and baking powder together. Carefully fold into the
egg mixture in three batches.
Pour the mixture
over the pineapple. Bake until a skewer inserted in
the centre comes out clean, about 30 minutes.
While still hot;
invert on to a serving plate. Serve hot or cold.