Toast loaded with butter and honey and a sprinkle of salt is really warming for me. I haven’t found anything else that yields a consistently noticeable boost when I feel cold though. The sugar/salt mix hasn’t done anything for me when I’ve tried it which made me sad as I’d had the idea to make a heavily salted salted caramel to use instead (I tried anyway and it didn’t help either).
When I wake up in the middle of the night and am really awake (happens 2-3 times a week) I need fat and a carb to go back to sleep, cheese and crackers or pretzels works pretty well and is easy for me to eat even when my very pregnant tummy is totally uninterested in food.