Combine sugar and 1/2 cup water, and boil until the sirup spins a thread.
Remove from the fire and pour in a thin stream into the beaten egg whites, and continue beating until the mixture is cold.
Add the flavoring and fold in the whipped cream. (Do not pour the whipped cream into the sirup egg mixture while the mixture is the least bit hot.)
After folding in the cream, pour the whole into a mold (aluminum is your best bet, as most of the so called "icebox glass" cracks when used for this recipe).
Pack in ice and salt for 2 hours, or place in a freezer unit for 1 to 1 1/2 hours, but watch to see that the parfait does not freeze completely.
The parfait should be topped with whipped cream or fruit juice.
Canned figs, frozen strawberries, fresh sliced and sugared peaches, or other such fruits are delicious for topping.
For variety, chopped nuts and dates may be combined with the fruit sirup for serving over the parfait, or they may be added before freezing.