Beat the room temperature butter with sugar and vanilla sugar.
Add the eggs, and beat.
- Add sour cream, and beat again until smooth and fluffy.
- In a separate bowl, mix 300g (10.50 oz) of sifted flour with baking powder and salt.
- Add dry ingredients to the liquid ones, and knead the dough with a spatula
- Squeeze the juice from the orange, and make the zest.
- Divide the dough into 2 parts.
- Into the bigger part add pumpkin puree, orange zest, 30 ml of orange juice and 50g (1.75 oz) of flour. Mix with a spatula.
- Add sifted cocoa and 80 ml of orange juice to the smaller part of the dough. Pour in the cream, and stir until smooth.
- Grease the baking tin with butter, sprinkle with cocoa, and shake off the excess ("French shirt").
- Pour two types of dough alternately into the center of the tin (2 tablespoons each).
- At the end, make random patterns on the surface of the dough using a toothpick.
- Bake the cake in the oven preheated to 356F (180C) for 20 minutes. Then reduce it to 320F (160C), and bake for another 40-60 minutes, depending on the size of the tin, until cooked (the skewer should come out dry!).
- Cool the finished cake on a wire rack, and serve.
* I recommend baking this cake in a larger pan (I have 18cm). Then it will be a little lower, but it will cook faster and more evenly!