Can almond milk be cooked down as a substitute for evaporated milk??

You can simmer almond milk to reduce and concentrate the flavor and texture: when reduced by half, it is approximately the thickness of heavy cream. Whether it can be substituted for evaporated milk will depend to some extent on the dish, but in general, you should be able to use it.

For more information and recipes:

Guide to Ingredient Substitutions.

Can you substitute almond milk for milk and buttermilk in cake recipes?

Recipe: Almond-Milk Rice Pudding