By JONATHAN CHADWICK FOR MAILONLINE

Whether you’re having beef, lamb or even chicken, no Sunday roast is complete without a Yorkshire pudding.
Recently named Britain’s most treasured regional delicacy, this delectable cup of cooked batter can be the trickiest item on the plate to get right.
Even chefs at top restaurants and pricey gastro pubs have been known to mess them up.
And is there anything worse than a Yorkshire Pudding that’s too flat, too dry or simply stone cold?
To mark National Yorkshire Pudding Day today, MailOnline has provided a step by step guide for making the perfect Yorkie, according to science.

According to scientists at the Royal Society of Chemistry (RSC), a Yorkshire pudding recipe has just five ingredients – plain flour, milk, water, eggs and salt.
The RSC’s recipe strictly requires plain flour – not self raising flour, which has baking powder added to it.
In fact, no baking powder or bicarbonate of soda should be added at all to the mix, because this can actually result in flatter, deflated puddings that haven’t risen properly.
‘One of the theories is that they will make the batter rise too quickly before the gluten has time to strengthen the mix and will then collapse,’ British food technologist and Yorkie fan Elizabeth Head told MailOnline.
Also, bicarb can turn the batter too ‘cakey’ or increase the risk of burning, according to RSC.
For the liquid, RSC claims chefs should use 92 per cent milk and 8 per cent water, rather than just milk as commonly done in the country’s kitchens.
The extra moisture from the water leads to lighter, puffier Yorkies, because the movement of the steam created by the heat encourages them to puff upwards.
No less important are the eggs, which also add moisture and act as an emulsifier, allowing the ingredients bind together.
Two eggs should be enough for a batch of six puddings, along with 250ml of the liquid (230ml milk and 20ml water), 85g of plain flour and half a teaspoon of salt.
Once the batter is whipped to a thin consistency similar to single cream, it must be kept at room temperature – not be placed in the fridge.
Mrs. Head told MailOnline: ‘Batter needs to be room temperature so that when it hits the hot oil you get a better rise.
RECIPE
The Royal Society of Chemistry’s Yorkshire pudding recipe
Ingredients (makes 6 puddings)
– 85g plain flour
– 2 small eggs
– Half a teaspoon of salt
– 250ml of milk and water mixture (230ml milk and 20ml water)
– 1 to 2 tablespoons of vegetable oil or beef dripping
Method
1. Put flour in a bowl, make a well in the middle, add the egg, stir until the two are combined then start gradually adding the milk and water combining as you go.
2. Add the liquid until the batter is a smooth and thin consistency.
3. Stir in half teaspoon of salt and leave to stand for 10 minutes
4. Put chosen fat into Yorkshire pudding tins or into one large tin but don’t use too much fat.
5. Put into hot oven until the fat starts to smoke.
6. Give the batter a final stir and pour into the tin or tins.
7. Place in hot oven until well risen – should take 10 to 15 minutes.
As the batter hits the hot oil it is easier for the oil to heat a room temperature batter than a really cold batter.
‘A cold mix will not rise as well and you will have a dense pudding.’

Whether you’re having beef, lamb or even chicken, no Sunday roast is complete without a Yorkshire pudding