Gregg Wallace is following production of a seasonal favourite, the Yorkshire pudding. Inside the factory in Hull, they produce five hundred million frozen Yorkies every year. Although the factory makes them by the tonne, the ingredients are as simple as when you make them at home – flour, eggs, milk and salt. But the processes are entirely industrial, with high tech mixers, a 53 metre-long conveyor oven and huge freezers.Gregg learns that the key to getting the perfect Yorkshire pudding shape is to trap air in the batter while mixing, and to make sure the oil added to the cooking pan forms a ‘halo'. Elsewhere in the episode, Cherry Healey visits one of the country's largest wheat testing and storage depots where each silo contains enough wheat to make flour for 416 million Yorkshire puddings. And if you prefer beef to your Christmas turkey, she teams up with food scientist, Barbara Bray to learn how to cook the perfect gravy for a Sunday roast. And historian Ruth Goodman bites into the history of the roast dinner; and helps a chef master the art of washing up Tudor-style.

Gregg Wallace explores the Jelly Bean Factory in Dublin to reveal the incredible processes it employs to make ten million colourful little sweets every day.Cherry Healey visits the University of Birmingham to learn about the important role glucose plays in our bodies, and she visits a lipstick factory to discover how one of the ingredients in jelly beans plays a key role in the production of her lippy.Historian Ruth Goodman is serving up the history of jelly and delves into the story of post-war pick‘n'mix.

Gregg Wallace visits two factories in Italy and Wales to explore the fascinating secrets behind how Welsh jeans brand Hiut make their trousers, learning how denim cloth is made and then transformed into one of the world's most popular items of clothing.Meanwhile, Cherry Healey visits a zip factory to learn how the ubiquitous fastener is made, and she heads to the research and development facility of a denim manufacturer to witness environmentally friendly ways of distressing denim to make a new pair of jeans look old.Historian Ruth Goodman discovers an unknown name in the history of jeans who helped to shape their design forever, and uncovers the fascinating history of indigo dye.