Sift together into bowl the flour, 1 cup sugar, baking powder and salt. Add oil, half cup milk and flavoring. Beat 1 minute and add rest of milk and egg yolks. Beat 1 minute.
In separate bowl, beat egg whites very stiff and add half cup sugar. Continue beating for 1 to 2 minutes to make a very stiff meringue. Fold meringue into batter. Pour into 9x13 pan and bake 30 to 35 minutes at 180ºC .