Breaking news. Listen up. B & I have come to the conclusion that this is the best cake in the world. Drop everything you're doing and get in the kitchen. Ottolenghi has made walnut and halva cake. I don't need to say any more.
Take a fluffy, yellow sponge, layer it with walnuts which have already been toasted in butter, cinnamon and brown sugar, cover the sweet, nutty heaven with chunks of halva (my new obsession. How have I got so far through life without it?), layer on more sponge, and the sprinkle on more of the magic walnut concoction. Sit by the oven as it bakes, just to make sure you didn't miss a single waft of spicy, warm comforting smells coming from the oven. Leave to cool and then slice carefully so you have a rustically perfect line of filling running down the middle of your piece.
Have as pudding, have with coffee, have as breakfast. And then bake another one because that one will have disappeared already.