It is totally up to you! I didn’t include any raisins and nuts in my recipe because I was out of raisins the day I baked this cake. Suppose you like raisins, pecans, and walnuts, feel free to add them in the last step. If you want to add nuts, I recommend toasting them beforehand, and then adding them to the cake batter right before transferring the batter to the cake pans.