Better then Bessie's
Home made usually means more work and sometimes for the amount of time and effort exerted, the results aren't great. But there are some things that shouldn't ever be store brought, it would just be wrong. Yorkshire puddings fall under the latter cooking category, they're so simple that there are no excuses AND they're better then any cardboard tasting, frozen version. Make them!
Ingredients:
-125g plain flour or Preferably strong plain flour
-½ tsp salt
-2 eggs, beaten
-300 ml milk or for a lighter batter I would

recommend using a mixture of equal parts milk

and water to make 300ml
-vegetable fat
Preheat the oven to 220ºC
Sift the flour and salt into a bowl and make a well in the center, add the beaten eggs
gradually mix in the flour from the sides and slowly add the milk/water mixture to make a smooth batter. For a very smooth batter work all the ingredients together with an electric whisk for a minute.
If you still have lumps you can sieve the batter through a fine-meshed sieve.
Cover and let the batter rest for 30 minutes or over night.
When ready to use (once your roast is cooked?) put ½ tsp of the vegetable fat (you could also use some sort of animal fat (lard) or cooking oil) in each cup of the Yorkshire pudding tin and heat at 220°C until very hot and almost smoking. This is important the fat has to be very hot or the Yorkshires will not rise! Quickly remove the tin from the oven and fill each cup half way with batter. Bake for 20-25 minutes, but don't be tempted to open the oven in the first 5-10 minutes.