This is a side to serve with your roast dinner, or can be used to cover some cooked sausages to make the main dish Toad in the Hole. The method is the same. You can make your Yorkshire Pudding as large or as small as you want. Standard is using a 12-cup muffin tin.
This is an unusual recipe, in that it requires equal volumes of the key ingredients: Eggs, flour and milk.
Choose farm fresh eggs, can't stress that enough. Here in the US, eggs on supermarket shelves are often stale by the time we buy them. Find your local farmers market or small grocery store. Fresh eggs have a higher water content, which is vital in allowing the batter to rise.
To make 12 "popover" Yorkshire Puds, use two eggs, and the same volume each of flour and milk. Best use either 2% (semi-skim) or whole milk, as there's not enough body to full skim.
The other key is to not open the oven door until the things have risen, which is at least 12-15 minutes. It's best to cook them after your roast is out of the oven and is resting and being carved, while you're making your gravy.
Increase your oven temperature to 425°F or even 450°F, and put a drizzle of fat in each cup of your muffin tin. Traditionally you would use the meat drippings, if you have vegetarian friends coming you would want to use vegetable oil or crisco.
Mix the eggs and flour together. This mixture will get a bit stiff, that's great as you are creating gluten for the puds to rise. Then add the milk and mix until it's silky smooth and bubbly. Some people rest this in the fridge, but for me it would lose bubbles, so I usually just prepare it when the oil is heating up.
Timing is vital next. Pull the pan out of the oven and quickly pour a couple of tablespoons of the mixture into each cup, and return it immediately to the oven. If your oven has a window and a light, use it, and set your timer to 12 minutes. Check the look of the puds and if necessary leave them a few minutes longer.
Serve with your roast dinner, vegetables and gravy.