Preheat oven to 375°F. Lightly grease a 13 x 9 x 2″ cake tin, line with wax paper and lightly grease paper. Sift flour with baking powder and salt. Beat egg whites until stiff, gradually adding the sugar. Add the egg yolks one by one, fold in dry ingredients and lastly the vanilla. Pour into tin and bake until golden (30 mins. approx.). Allow to cool, cut into squares and cover with following syrup.
Heat sugar, water, cinnamon, lemon juice and peel, and boil for 5 mins. Remove from heat, add vanilla and cool. Add liqueur before pouring over cakes. Makes 12.