Crush your walnuts. Do this by either placing your nuts in a bag, and bashing with a rolling pin. Or, blitz them in a food processor. Put them to one side for a short while.
Pre-heat the oven to 175ºC (350°F).
Grease and line 2 x 7" (18cm) cake tins (you can use two 8" pans but the layers will be thinner).
In a food processor, or by hand, beat the sugar and butter together until light and fluffy.
Add the eggs, one at a time.
Combine the walnuts, flour, baking powder and baking soda.
Fold into the wet ingredients.
Mix the coffee and milk together then mix into the batter. A fairly soft dropping consistency should be achieved (add a little more milk if needed).
Divide the mixture equally between the two pans and then bake for around 30-35 minutes (if baking 8" cakes, bake for 20-25 minutes).
The cakes are ready when they bounce back after being gently pushed down (or an inserted skewer comes out almost clean).
Remove from the oven and let them cool for about ten minutes.
If using spring-form pans, remove the sides until the cakes are fairly cool and then turn out onto a wire rack (top side down) until they are completely cold.