Put the water and granulated sugar in a sauce-pan. Have ten of the apples pared and cored, and as soon as the sugar and water boils, put in as many of the apples as will cook without crowding.
Simmer gently until the fruit is cooked through. When done on one side the fruit must be turned. Drain, and cool them on a dish. Cook ten apples in this manner.
Have the six that remain pared and quartered and stewed in one cupful of water.
Turn the stewed apples into the syrup left from cooking the others. Add the grated rind and the juice of the lemon. Simmer until a smooth marmalade is formed. It will take about twenty minutes. Set away to cool.
Put the milk on in the double boiler, reserving half a cupful. When it boils, stir in the corn-starch, which has been mixed with the cold milk. Stir well, and cook five minutes.
Beat the yolks of the six eggs and the whites of two with half of the powdered sugar. Gradually pour the boiling mixture on this. Return to the boiler and cook three minutes, stirring all the time.
Add the salt. Turn into a pitcher or bowl, and set away to cool.
Heap the cooked apples in a mound, using the marmalade to fill up the spaces between the apples.
Beat the four whites of eggs to a stiff froth, and beat the half cupful of powdered sugar into it.
Cover the apples with this, and stick the almonds into it. Brown slowly in the oven. Set away to cool.
At serving time, season the custard with lemon, and pour it around the porcupine.