Pineapple and Ginger Upside-Down Cake

Pineapple and Ginger Upside-Down Cake

Ingredients: 225 g (8 oz) soft butter, plus extra for greasing 200 g (7 oz) caster (superfine) sugar 4 eggs, separated 20 g (¾ oz) grated fresh ginger 1 teaspoon vanilla extract 220 g (8 oz) plain (all-purpose) flour ½ teaspoon salt 2¼ teaspoon baking powder ½...