The employee based in the UK posted a video on TikTok to show the secrets behind the delicious sauce, MailOnline reports.

In the video TikTok user @cheddar4.7 pours a jug of water onto what they call ‘crackling’ – claiming it is pieces of chicken which fall to the bottom of the fryer and go crispy.

They then add a sachet of gravy spices – the exact contents of which is unknown – to the mixture and mix everything together.

It is placed in the oven for 18 minutes and then whisked, then put back in the oven for another nine minutes before being whisked again and poured through a sieve to remove large pieces.

The gravy is then placed into KFC’s signature red-topped gravy pots and stored for up to six hours.

The video has received swathes of comments from TikTok users, some calling it ‘grim’ and others claiming they will ‘never buy it again’.

Another added: ‘I wish I never saw this,’ while another said they were thankful that they were a vegetarian.

But other viewers expressed confusion at the comments of disgust, with one saying: ‘People in the comments obviously don’t understand what gravy is.’

‘This is so much better than I thought it was made. Can’t imagine what some people in the comments would think if they saw how normal gravy is made,’ another added.

The staff member’s video even caught the attention of fellow KFC workers, who critiqued how it was made: ‘The crackling is supposed to be left to let the oil drain out. That looks minging.’

The TikTok user has also revealed other behind-the-scenes clips from the fast food chain, including how fillet burgers and mini fillets are made.

The videos come after other workers in popular chains filmed TikToks showing how popular dishes are prepared.

Wetherspoon employee J Salsa, 19, uploaded videos of himself preparing a chicken curry in the microwave and cooking customers full English breakfasts, paninis and deep-fried halloumi chips.

Many were shocked to discover their favourite meals had been prepared in the microwave, with the chef revealing only meat and eggs are cooked fresh on-site. He was later fired from the company.