Preheat the oven to 170°C/ Fan 150°C/ Gas Mark 3

First, crack the eggs into a food mixer along with the caster sugar and whisk on medium to high speed until white, thick and fluffy - this should take approximately 4 - 5 minutes. In the meantime, zest and juice 2 of the oranges and 2 of the lemons - set aside until needed.

Once the eggs are light and fluffy, combine the oil, citrus juice and zest in a jug and then slowly pour into the egg mixture whilst continuously whisking. Do this stage very slowly to ensure the eggs do not split.Once the eggs are light and fluffy, combine the oil, citrus juice and zest in a jug and then slowly pour into the egg mixture whilst continuously whisking. Do this stage very slowly to ensure the eggs do not split.

In a separate bowl, sieve together the ground almonds, self-raising flour and salt. Add the chopped rosemary to the flour mixture before gently folding into the egg and oil mixture with a metal spoon until all the ingredients are completely combined into a light and fluffy batter.

Lightly grease the heritage dish with a little butter before gently pouring in the batter. Thinly slice the remaining orange and lemon and gently place the slices on the surface of the batter ensuring they do not sink into the batter.

Bake in the oven for 1 – 1 hour 15 minutes, until golden and when a skewer is inserted into the centre of the cake, it comes out clean. If the cake is browning a little too quickly, simply cover with a little foil and return to the oven until fully baked.

When ready, remove the cake from the oven. Carefully run a knife round the edge of the dish for easy release later and using a skewer poke a couple of holes in the top of the cake for the syrup glaze.v

For the glaze, warm the lemon juice in a pan over a low heat or in a microwave and stir in the sugar until dissolved. Gently brush the top of the cake with the syrup glaze and allow to fully cool before slicing and serving with a little icing sugar.