Aquafaba (or the liquid from a can of beans) firms up the texture a little although if you don’t have aquafaba on hand then non-dairy milk will work just fine.
Butter or margarine: I’ve omitted vegan butter or margarine that is traditionally called for in this recipe as coconut milk adds a lot of richness already. Feel free to spread the bread with some vegan margarine (prior to cutting it) for a more indulgent and rich dish if you are using other non-dairy milk. Or just leave this out completely for a lighter version.
Any stale bread will work for this recipe. Different types of bread will require slightly more or less milk to soak the bread. Adjust the amount as required.
The choice of non-dairy milk will affect the taste and texture. My preference is for coconut milk for its richness and fragrance. If you are using homemade coconut milk (like I did), make the milk to a thicker creamier consistency by reducing the ratio of water to coconut flakes. Else use one can [400 ml] thick