Odd question I know but I want a light colored beer to be the look of milk :o. I am thinking outside the box for a white stout recipe and the ones I have seen are more yellow with a thick white head.
Turbid mash could help.
Look up some best practices for a wit or an east coast ipa? Wheat flour? Oats?
Fruit pectin causes a nice haze as well. For milky your going the neipa route though.
There's a "deconstructed stout" recipe in the DIY Dog pdf. I don't think it's white but might give you some ideas on ingredients.
Also a big dry hop along with oats and wheat will help