Ingredients:
1. 200 g butter at room temperature
2. 200 g sugar
3. 4 eggs
4. 200 g wheat flour
5.1 teaspoon baking powder
6. Grated zest of 2 oranges
7. 100 ml orange juice
8. 1 teaspoon vanilla essence (optional)
Icing (optional):
1. 150 g powdered sugar
2.3-4 tbsp orange juice
