Preheat the oven to 180C and grease and line the bases of 2 x 18cm sandwich tins.
Put the melted butter, sugar and eggs into a large mixing bowl and whisk well until the ingredients are thoroughly combined and the mixture has almost doubled in volume.
Sift together the flour, bicarb, salt and spices and then fold very gently into the liquid mixture, being careful to knock as little air out as possible. Fold in the remaining ingredients and divide between the tins. Bake for about 30 minutes until a skewer inserted into the middle comes out clean. Cool in the tins.
Meanwhile, beat together the icing ingredients and refrigerate. When the cakes are cool enough to ice, remove from the tins, top one with half the icing, and then the other cake. Ice the top, and decorate with the remaining pecans.