Boil some peeled and cored apples until tender; press them through a colander; season to taste with butter, sugar, and vanilla. Place the puree in a granite-ware saucepan and let it cook until quite dry and firm. To one and one quarter cupfuls of the hot reduced apple puree add the whites of four eggs, whipped very stiff and sweetened with three tablespoonfuls of powdered sugar. Mix the puree and meringue lightly and quickly together and turn it into a pudding-dish; smooth the top into a mound shape; sprinkle with sugar and bake in a slow oven twenty to twenty-five minutes. This souffle does not fall. Serve with a hard, a plain pudding, or an apricot sauce.