Fact.
Cooking is all about science, whether the chef knows it or not.
A good cook, through knowledge and experience, knows the right consistency for this, and the correct cooking time and temperature for that, and knows good quality ingredients.
In scientific terms, he has excellent control of the variables.
In terms of yorkshire pudding, there are many opinions as to what it should be - some say light and airy throughout, others crispy outside and a bit of 'clagger' in the middle. Others still say crisp on top and solid at the base.
Depending on how you define the 'perfect' Yorkshire pudding, then there will be different ways of preparing / cooking it (how much beating the mixture (adds air), temperature of the oil, ratio of egg to milk etc etc.). There are sound scientific reasons why varying this or not doing that will affect the end result.
A good chef may not know the science behind it, but he knows the effects of each action or ingredient.