Cream cheese and walnut is the tea sandwich that adds crunch back into a filling built to have none. Soft cream cheese is spread on thin brown bread and studded with chopped walnuts, and the whole point is the collision: a cool, smooth, faintly lactic spread carrying small hard pieces that resist the bite. Cream cheese alone on bread is one texture and one mild note. The walnut is what gives the sandwich a second thing happening, a bitter, slightly tannic snap against the smoothness, and it is the reason this has a name of its own rather than being filed as plain cream cheese.
The craft is in the chop and the bind. The walnuts have to be chopped fine enough to distribute through every bite but left coarse enough to keep their snap, because a walnut ground to dust just tints the cheese brown and surrenders the texture the sandwich exists for. The cream cheese does structural work as well as flavour work: it is the mortar that holds the loose nut against the crumb so the filling does not shed when the sandwich is cut, and it is spread to the edges so no bite is bare. Brown bread is the deliberate choice over white here, its nuttiness running with the walnut rather than against it, and the crusts come off so nothing with real chew competes with a filling whose only firm element is the nut itself. A little softened butter under the cheese seals the bread, but the spread is kept thin, because a thick slab reads as cloying and slides.
The variations stay inside the soft-spread-plus-crunch frame. A thread of honey or a few chopped dates push it toward the sweet end; celery traded for or added to the walnut keeps the crunch but turns it savoury and watery-fresh; a firmer cheese folded through changes the body without losing the contrast. Each is a distinct named pairing on the tea tray and deserves its own article rather than being crowded in here.