Soup is easy to make in batches; legume-based soups freeze well and others freeze at least tolerably. Measure out servings into (well-sealed) tupperwares and freeze them; chuck one into your backpack come morning. Pasta salad, potato salad, egg salad, or tuna salad can also be made in large amounts—they won’t freeze as nicely, so you’d want to put them next to your frozen soup or one of those things that you put in lunchboxes to keep stuff cold.
Soup is easy to make in batches; legume-based soups freeze well and others freeze at least tolerably. Measure out servings into (well-sealed) tupperwares and freeze them; chuck one into your backpack come morning. Pasta salad, potato salad, egg salad, or tuna salad can also be made in large amounts—they won’t freeze as nicely, so you’d want to put them next to your frozen soup or one of those things that you put in lunchboxes to keep stuff cold.