Whole-Wheat Sponge Cake with Fudge Filling

• 90 g / 3 oz light muscovado sugar
• 1 tbs clear honey

Measure the sugar, honey, vanilla essence, egg yolks and hot water into a bowl. Whisk until light and foamy with an electric beater or food mixer. In a separate bowl, whisk the egg whites until stiff, then fold into the yolk mixture. Tip the flour into a sieve and shake a fine layer over the mixture. Fold in gently and repeat until only bran remains in the sieve. Fold in half the bran and retur