Wow, thanks for that insight! I hadn't thought of it that way before, but it makes a lot of sense, although it paints an incredibly sad picture of poor young Severus.
Maybe as an adult, he learned to cook out of necessity when he wasn't working at Hogwarts? If he lived off biscuits, tea, and chocolate bars as you suggest, it might explain why he doesn't look too healthy. Even if he did cook, I don't see him taking a lot of pleasure in food, with all the responsibility and guilt weighing him down. Maybe he doesn't feel that he deserves any pleasures in life after he caused Lily's death--except maybe for giving detention to unruly Gryffindors!
Maybe as an adult, he learned to cook out of necessity when he wasn't working at Hogwarts? If he lived off biscuits, tea, and chocolate bars as you suggest, it might explain why he doesn't look too healthy. Even if he did cook, I don't see him taking a lot of pleasure in food, with all the responsibility and guilt weighing him down. Maybe he doesn't feel that he deserves any pleasures in life after he caused Lily's death--except maybe for giving detention to unruly Gryffindors!