Use their eggs for this full-flavoured super sponge.
8 duck eggs or size hen eggs
the weight of 5 eggs weighed in their shells in sugar
the weight of 3 eggs weighed in their shells in flour
Line a 20cm square tin with baking paper on the bottom. Then, tie with string a sleeve of baking paper around the outside of the tin so that it comes 7cm above the edge of the tin.
Separate the eggs. Beat the yolks and sugar for 20 minutes. By hand is the best method, but you can cheat and use an electric mixer if you like. The mixture will take on a gorgeous coral colour and is ready when the mixture retains an impression of your spoon or whisk for a few seconds.
Beat the egg whites until stiff and fold gently into the sugar and yolk mixture.
Sift the flour, then fold bit by bit into the mixture. Don’t beat or overmix – you want to keep the lightness of the sponge.
Bake at 175ºC for 1 1/2 hours. For the first hour, place the cake in the top half of the oven, then move down to the lower shelf for the remaining time.