Preheat the oven to 180°C (fan 160°C)/350°F/gas mark 4.
Grease a 23cm spring form cake tin with the extra oil and line the base and sides with baking parchment.
In a mixing bowl, combine the ground almonds, caster sugar, cinnamon, ground cloves and baking powder.
Using a fine grater, grate the zest from the lemon and oranges into the mixture, combining well.
Break the eggs into a container and lightly whip, then add these and the oil to the dry mix until well combined.
Pour the cake mixture into the prepared tin, and bake in the preheated oven for one and a half hours.
Cover the top with a piece of foil after about 20 minutes, then remove the foil about 20 minutes before the end.
Meanwhile, make the syrup. Squeeze the juice from the zested lemon and oranges into a small pan.
Add the sugar and spices, mixing together well.
Bring to the boil, then reduce the heat and simmer for 3 minutes.
Once the cake has been removed from the oven, pierce it several times with a skewer.
Using a tablespoon, spoon the syrup over the cake, allowing it to soak in. You might not need all the syrup.
Leave the cake to cool.
For the topping
Break the chocolate into small pieces and place in a bowl over a bain-marie
When melted, stir in the oil.
Using a spoon and palette knife, spread the chocolate thinly over the top and sides of the cake, then sprinkle the mixed peel over the cake top.