Preheat oven to 350 degrees and grease two 9-inch cake pans.
Optional - Roast the nuts slightly on a baking sheet in the oven while it preheats for up to five minutes. Remove the nuts and allow the nuts to cool.
Put the sugar and butter into a bowl and mix by hand or with an electric mixer on high speed until creamy.
Stir in the blackberry jam.
Add in the eggs. Beat them one at a time into the mixture until they are thoroughly combined before adding in the next egg.
Set aside 1 tablespoon of flour.
Sift the rest of the flour into the mixing bowl.
Stir in all the dry spices you are using, and the salt.
In another mixing bowl, combine the buttermilk and the baking soda. Stir until they baking soda is dissolved.
Add in a third of the flour, spice, and salt mixture and combine.
Pour in half of the buttermilk mixture and combine again.
Add in another third of the flour mixture and the remaining buttermilk mixture and combine once again.
Add in the last of the flour mixture and combine completely with the other ingredients in the bowl.
Mix together the roasted nuts, the 1 tablespoon of flour, and raisins - if your are using them. Make sure the nuts and raisins are completely coated and fold them into the icing. Split the icing in half so it can be placed on the middle and top of the cake.
Pour the batter into the greased cake pans and place in the oven for 40 minutes.
Remove the cakes from the oven and allow to cool for 10 minutes before flipping them over onto baking racks.
Let the cakes rest on the cooling racks for at least 20 minutes before frosting them with icing.