Preheat the oven to 180°C. Line the bottom and sides of a 23cm cake tin with baking paper.
Sift flour, baking powder and a pinch of salt together onto a piece of paper. Peel, quarter and core apples, then slice finely, putting slices in a large bowl with the lemon juice. Toss them often to make sure they are coated with lemon juice.
Break eggs into a bowl and whisk with an electric beater for 1 minute, then whisk in the sugar a tablespoon at a time. Continue whisking until pale, thick and mousse-like, and mixture forms a ribbon when beaters are lifted out (the mixture should fall off the beaters in a thick trail).
Chop rosemary leaves (if chopped in advance they blacken) and measure 1 tsp. Sift half the dry ingredients over the egg mousse and fold in with a large spoon, then sift the rest over and fold in. Sprinkle over lemon zest and rosemary. Pour the butter around the sides of the cake batter (rather than dumping it all on the top which can deflate the batter), add sliced apples and gently fold everything together until the butter is just mixed in. The mixture should still be light and fluffy.
Turn mixture into prepared tin. Bake for 35-40 minutes, until golden brown on top and shrinking slightly from the sides of the tin. The cake should feel springy to the touch. Leave in the tin for 5 minutes to settle, then turn out onto a plate and peel off paper. Cover cake with a fresh piece of baking paper then a cake rack, and flip over again. Leave until cool. Dust with icing sugar before serving.
One of the first cakes I made for Remo’s family was a whisked sponge. I was fresh out of Le Cordon Bleu School in London and wanted to show off. I didn’t have an electric beater so I whisked the eggs and sugar with a hand whisk. The result was spectacular (thank God) and I got the thumbs up. Italian cakes are often overly sweet, but a savoury note, in this cake from rosemary, helps balance that.
Article from the July, 2012 issue of Taste magazine.