Preheat oven to 180 degrees C. Grease and flour two 22cm cake tins.
In a large bowl cream together the butter, brown sugar and white sugar until light and fluffy. Beat in the eggs one at a time then stir in 2 teaspoons vanilla.
Sift together the flour, baking powder, bicarbonate of soda, salt, cinnamon, nutmeg, cloves and allspice. Set aside.
Beat the flour mixture into the butter mixture alternately with buttermilk mixing just until incorporated. Stir in pecans. Pour batter into prepared cake tins.
Bake in the preheated oven for 35 to 40 minutes or until a toothpick inserted into the centre of the cake comes out clean. Let cool in tin for 10 minutes then turn out onto a cake rack and cool completely.
Icing: In a large bowl combine butter, salt, vanilla and about 1 cup of the icing sugar. Beat well then gradually beat in the remaining icing sugar alternately with buttermilk. Beat until smooth and creamy and spread on cake.