Instructions
Set your oven to preheat to 190 degrees Celsius (Gas Mark 5). Lightly grease a 23cm round springform cake tin. First, prepare the orange. Use a knife to carefully cut off the hard ends from the top and bottom of the orange. Slice the entire orange into small pieces. Remove any seeds you find. Place all orange pieces, including the peel, into a food processor. Blend until it becomes a smooth puree. Add 100g of caster sugar (one third of the total) and the 75ml of olive oil to the orange puree. Blend again until these ingredients are well mixed. In a separate bowl, sift together the 280g of flour and 1 tablespoon of baking powder. Set this aside. In a large mixing bowl, combine the 4 eggs and the remaining 200g of caster sugar. Use an electric hand mixer to beat this mixture for at least 5 minutes. Beat until the mixture is very light, pale, and fluffy. Gently fold in half of the sifted flour mixture. Next, add the orange puree mixture and 2 teaspoons of vanilla extract. Gently fold these in. Finally, fold in the remaining half of the flour mixture. Mix carefully until all ingredients are just combined. Do not overmix. Pour the cake batter into the greased 23cm springform tin. Use a spatula to gently smooth the top of the batter. Place the tin into the preheated oven (190°C). Bake for 20 minutes. After 20 minutes, reduce the oven temperature to 160 degrees Celsius (Gas Mark 2). Continue to bake for another 30 minutes. The cake is done when it looks golden brown and a wooden skewer inserted into the center comes out clean. Remove the cake from the oven. Let it cool completely on a wire rack before serving.