Cook trimmed green asparagus spears in salted water until just tender. Melt a generous knob of butter in a frying pan and add finely whizzed brioche crumbs with the grated zest of ½ lemon. Stir and toast until golden. Season and scatter over the drained asparagus. You could also serve the cooked asparagus with blender hollandaise or gorgonzola sauce.