For the casserole with pineapple, cut the pineapple slices in half and drizzle them with lemon juice.
Soak the bread slices in the mixture of beaten egg, grated zest of a lemon or lime, half of the sugar and milk.
Grease a baking dish with butter and place half of the bread in it. Cover this with the pineapple and place the rest of the bread and mixture on top as a smooth layer.
Separate the eggs, whisk the two yolks with the rest of the sugar until foamy and fold in the stiffly beaten egg whites. Cover the baking dish with this.
Place the casserole in the oven for about 30 minutes at medium temperature until lightly browned.