Preheat the oven to 350 degrees. Melt the butter in the pans. Remove 1 tbsp and set aside. Add the borwn sugar and stir until blended. Add drained pineapple slices on top. In a bowl, whisk together the egg, butter and lemon rind. Beat eggs white with the salt until stiff. Fold in the sugar, 2 tbsp at a time. Fold in the egg yolks. Sift the flour and baking powder together. Fold into the egg mixture in 3 batches. Pour the batter over the pineapple. Bake about 30 minutes. Flip over while hot.