Ingredients
Method
1.Combine sugar and water in a large saucepan and stir over medium heat until sugar dissolves. Bring to the boil. Boil, uncovered, without stirring, for 10 minutes, until a lovely caramel colour. Keep a close eye on the pan. Add the butter and stir briskly with a metal spoon. Be prepared for the mixture to froth up.
2.Meanwhile, preheat the oven to 180°C/160°C fan forced. Grease a deep 22cm round cake pan and line base and side with baking paper.
3.Finely grate the rind from oranges. Peel oranges, removing all the white pith. Cut oranges in half from top to bottom, then cut out the centre in a V-shape to remove white membranes. Cut into 1cm slices. Arrange orange slices over base of pan. Pour caramel over oranges.
4.Using electric beaters, beat unsalted butter, rind and extra sugar in a medium bowl until light and fluffy. Add eggs, one at a time, beating well after each addition. Stir in dry ingredients and sour cream in two batches. Spread batter carefully over oranges and smooth the top.
5.Bake for 1 hour 10 minutes, until a skewer inserted into the centre of the cake comes out clean. Stand for 10 minutes, then invert onto a serving plate.
