- Pre -heat the oven to 180 degree C and line round cake pan with parchment paper. In a bowl whisk together flour and baking powder and set a side. In a separate bowl add the yogurt and sprinkle baking soda over it and set it aside to foam up. Whisk together castor sugar and oil in a separate bowl until pale and well combined. Now pour the yogurt mixture to the oil and sugar mixture and mix well. Add the vanilla extract. Gently fold in the flour and mix until everything is well combined. Add the walnuts, tutti frutti in the batter and transfer the batter to the prepared cake pan. Bake at 180 C for 30-35 minutes. Once done let it cool and cut into pieces and serve.