Apple and Walnut Crumble

Crumble is a good way to start fiddling about with the idea of a crust: it’s pastry really, only without the fear factor. Just plain, it’s wonderful enough, especially on those grim days with saucepan-lid skies in late November and early February, but it’s truly good as expanded here, with the nubbliness of the nuts and the almost honeyed crunchiness of the brown sugar. For two people who are wisely eating this with custard (see here if you intend to make your own), ice-cream, crème fraîche