The chocolate-shelled, gooey-centred Cadbury Creme Egg is an Easter favourite. But have you ever stopped to wonder what that gloopy, sweet liquid inside is actually made of? 

You can count on Twitter to start a conversation that captures the collective attention of social media over a holiday season. 

This Easter, the following questions have prompted a barrage of commentary and sugar-fuelled wonderment. 

"I have a huge problem weighing on my mind: What is the substance in the middle of a Creme Egg called? What is it? A goo?" someone has asked, while another tweeted: 

"I have a question. What is the goo made from in a Creme Egg?" 

While some suggested it's "frosting" or "toothpaste", according to the New York Post, that sickly sweet goop inside a Creme Egg is actually made of fondant. 

The New York Post reports that, according to the Cadbury company, the ingredients list includes: "sugar, milk, glucose syrup, cocoa butter, invert sugar syrup, dried whey, vegetable fats and dried egg white." 

Cadbury's Creme Eggs seen on the production line at the Bournville Cadbury factory in Birmingham, UK. Photo / Getty Images 

Not surprisingly, this means a Creme Egg's sugar content is through the roof. 

According to American paediatrics professor and author of "Sugarproof", each beloved egg has more than 6.5 teaspoons of total sugar and 6 grams of fat per egg. If you're calorie counting, one egg has 170 calories. 

The not-so-sweet revelation appears to have shocked Creme Egg fans on social media. 

"Just found out that Cadbury's Creme Eggs have got loads of sugar in them. Really upset about this, had no idea," wrote one former fan. "Someone has just told me that the centre is actually JUST sugar in which case why call it fondant smh." 

And another mused: "Why are people always using refined white sugar when you can just crack in a few Cadbury Creme Eggs?" 

Not everyone seems to be fussed about Creme Eggs, however: "Ate a Cadbury Creme Egg. Forgot how much I hated the slime on the inside. Reese's Eggs are superior." 

New Zealand has imported Cadbury Creme Eggs from the UK since 2010. At the time, the Herald reported "following a shake-up of the confectionery giant's operations last year, Creme Eggs are no longer made in Dunedin for distribution around New Zealand and Australia, as they have been since 1983."