From looking at the recipe photo and reading the method, it seems that the Green Eggs batter is kind of like a crepe batter. Therefore, I wonder if I should rest the batter as we do crepe batter? For an hour or overnight?
Nigella's recipe for Green Eggs And Ham (from NIGELLA EXPRESS) is perfect for a fun weekend breakfast with children. The "green eggs" are actually thin crepe-style pancakes that have been tinted green with the addition of pesto. The crepes are then filled with slices of ham before serving.
Crepe batter can be made in advance and rested, though there are many views as to whether it is necessary or not. In our experience crepe batter can be used immediately but if you have time then resting it for a while will let the flour absorb the liquid more evenly and let the bubbles in the batter subside, meaning the crepes are less vulnerable to tearing when cooked and turned over. So if you have time to rest the batter then it should be fine to do so. If resting the batter for more than one hour then it must be covered and left in the fridge. You may find that if the batter is rested overnight then it becomes a little thicker and you may need to add a splash of extra milk to thin it very slightly again.