Preheat oven to 180 degrees C. Grease and flour a ring tin.
Cream together butter, 2 cups brown sugar, vanilla and eggs. In a separate bowl combine flour, baking powder, soda, salt and cardamom. Slowly combine the dry and wet mixtures then fold in nuts, cinnamon and additional brown sugar.
Pour into prepared ring tin then bake in the preheated oven until a knife inserted into the centre comes out clean, about 45 minutes.