Preheat oven to 180°C Grease and flour a large loaf pan.
Beat egg yolks until thick & creamy. Gradually add vanilla and powdered sugar. Add dry ingredients and butter, beating with an electric mixer for 3 minutes on high speed, scrape down sides of bowl once or twice to ensure thorough mixing.
Whip egg whites until stiff and fold them lightly into batter. Spread mixture into prepared loaf pan. Bake for 20 - 30 minutes: until it tests done (by a toothpick coming out clean when poked into it.).
Combine sugar and cornstarch in a saucepan. Whisk in sweet pomegranate juice. Bring to a boil, whisking continuously. Boil for about 2 minutes, until smooth thick and glossy. Remove from heat and stir in rosewater. Chill.
To serve: brush a plate with pomegranate sauce and arrange 2 or 3 overlapping thin slices of cake over the sauce.