Ascorbyl palmitate is an ester made by joining ascorbic acid (vitamin C) to palmitic acid, a common fatty acid. The fatty part lets it dissolve in fats and oils, where ordinary ascorbic acid would not. It is INS 304 and, in the EU, E304, and Codex lists it as an antioxidant.
In fats it slows the oxidation that leads to rancid, stale flavours, and it is often used together with tocopherols because the two reinforce each other. Arnott’s cookies on SeekSnack show this pairing: Arnott’s Good Time Double Choc and Classic Chocochips list ascorbyl palmitate next to dl-alpha-tocopherol (INS 307c), lecithin and a raising agent.
