Beat the sugar and butter (or margarine) in a large bowl until pale and fluffy.
Add the beaten eggs.
Beat until smooth
Sieve the flour into the bowl
Gently fold through.
Add the zest of 1 orange and the juice of 1/2 an orange.
Gently fold through until evenly distributed through the batter.
Grease a 20cm loose-bottomed cake tin and line with baking paper. Spoon the batter into the tin and level off.
Bake at for 20-25 minutes until the cake has gently risen and turned golden brown. It should feel firm at the centre and you can check it is cooked through by pushing a skewer into the centre of the cake. It should come out clean.
Use a skewer or cocktail stick to poke holes all over the hot cake, almost to the bottom.
Put the juice of 1 orange in a microwave-safe bowl with the icing sugar, mix well and microwave for 60 seconds until you have a syrup. Note: it will be VERY hot, so handle with care.
Spoon or pour the hot syrup all over the hot cake and allow it to sink in. Leave to cool completely.
If you want a really crunchy topping instead of a syrup that sinks in, you’ll need to change the method slightly. Use granulated sugar instead of icing sugar and without any heat, mix your orange juice and sugar together to form a paste, then spread over the warm cake. This should give you your crunchy topping once cooled.