The answer is Butter Buds.
They come in a box of eight half-ounce packets (about a tablespoon). Box says they are made by the Butter Buds Div. of Cumberland Packing in Brooklyn, NY. I have bought them in regular supermarkets in several states.
A packet of Butter Buds, a tablespoon or two of regular (skimmed) powdered milk and the same of flour in about 1/8 to 1/4 cup of water (usually leftover cooking water) make a decent white sauce, and with powdered cheese added, it will turn Ramen noodles into passable Ramen n' cheese. Also other Italian-style pasta dishes (with dried veggies call it primavera for instance).
No issues with spoilage, even in extreme heat.