To prepare the oranges for the cake: Place the oranges into a large saucepan (I used a stockpot, but something the size of a Dutch Oven would do), cover oranges with hot water from the tap, place on a medium heat, and bring water up to boiling point. I had a problem with the oranges floating, so I placed a heatproof glass pie plate on top to keep them submerged. Reduce heat and simmer oranges for 40-50 minutes or until the skin is very tender - your fingernail should easily penetrate the skin. Check water from time to time and top up if necessary. Remove oranges from pan and allow to cool, then cut oranges into quarters, remove any seeds, and leave on a plate, uncovered, at room temperature, to dry a little for 1-2 hours. Now, unless you're going to make the cake immediately, place the orange quarters into a sealed container and store in the refrigerator until needed. To make the syrup: The syrup will keep so it can be made well ahead. Just place the orange juice, sugar and sauternes in a saucepan over a medium heat and stir until the sugar dissolves. Reduce the heat and simmer for 20 minutes until the liquid is reduced by half. From time to time, and especially at the end, scrape off any scum that forms on the top. Pour into a heat proof jug or jar, cool, cover and refrigerate until needed. Note: the syrup is supposed to thicken as it cools, but don't expect a thick syrup. To make the glace oranges: Remove any seeds from the orange slices and arrange them (with the rind still on) in a large, shallow, heatproof container. Cover oranges with boiling water and allow to stand at room temperature overnight. The next day, drain the oranges. In a large frying pan, place the sugar, water and vanilla bean and stir over a low heat until the sugar dissolves. Now, add the orange slices in a single layer, and simmer, uncovered over a low heat for an hour. Remove oranges and arrange in one layer on a plate and cover with the syrup. Cover and keep in the refrigerator until you want to decorate the cake - I did this just prior to serving it. If you find, as I did, the syrup went toffee-ish and the oranges stuck to the plate after keeping, just whack it, uncovered, into the microwave for a minute or so to melt the syrup. To make the cake: Spray a 22cm (9") springform tin with a double layer of silicone (baking) paper. Preheat oven to 170°C. Now, put the boiled orange quarters (peel and all) into a food processor and pulse until quite smooth - you won't get it completely smooth, but do your best. Add the eggs and pulse again, trying to get the smoothest mixture possible. Add the sugar, the flour (if using), the baking powder and as much of the almond meal as you can without overloading your food processor and pulse until you have a smooth batter. If necessary, pour batter into a big mixing bowl and stir in the rest of the almond meal. Pour the batter into the prepared tin and bake at 170C for 45-50 minutes or until a skewer, inserted in the centre, comes out clean. Allow to cool a little, then release the springform pan, and invert the cake onto a dinner plate and carefully remove the baking paper from the base and sides. Invert back onto another plate, allow to cool, then cover and refrigerate until needed. To decorate cake: Use your own judgement, but this is what I did. Pour a couple of tablespoons of the sauce over the top of the cake and smooth with the back of a spoon. Cut some of the glace orange slices into halves and arrange around the outside of the cake. Leave three or four slices whole, cut halfway through and then 'twist' to sit upright in a circle in the centre of the cake. Using a pastry brush, use the syrup from the glace oranges to glaze the sides of the cake - microwave the syrup briefly to bring it back to liquid consistency if necessary. Tuck some pretty flowers (I used daisies) amongst the oranges on top of the cake. To serve: Serve small slices (it's rich) with the syrup (cold or at room temperature) and a dollop of thick cream. Swear never to make this cake again!