1. Heat the oven to 180C/fan 160C/gas 4. Butter and line two 20cm round cake tins. Mix the coffee with 1 tbsp of just-boiled water in a small bowl and leave to cool slightly. In a large bowl, beat together the butter and golden syrup until well combined and fluffy. Add the eggs, one at a time, mixing well between each addition, then pour in the coffee mixture and add 50g of the walnuts. Fold in the flour, almonds and baking powder. Spoon equal amounts into the prepared tins and bake for 20-25 minutes or until a skewer inserted into the middles comes out clean. Set aside to cool completely in the tins.
2. To make the icing, mix together the coffee and 1 tsp of just-boiled water in small bowl, then set aside. Whisk the butter using electric beaters for 2 minutes until pale, then add the icing sugar. Whisk for another 2 minutes until light and airy. Pour in the cream and coffee, and whisk slowly until everything is combined and the cream forms soft peaks.
3. Put one cake on a serving plate and spread over half of the cream. Put the second cake on top. Spread the remaining cream over the top and sprinkle over the remaining walnuts.