Yorkshire puddings come out best when the batter has been rested for at least one night; however, they can be cooked immediately after forming the batter if time requires it. Form the batter as directed in step 1 and immediately proceed to step 2 without refrigerating it. The quantity of batter doesn't divide easily into standard 6-well popover pans, but you can scale up the recipe by 50% in order to make a full 12 popovers instead of 8. If using skim or low-fat milk, omit the water and increase amount of milk to 200g (7 ounces; 1 cup minus 2 tablespoons).
