Big Narstie completed the signature and technical challenges in the first part of the competition, but when it came to the showstopper he was nowhere to be seen.
"There has been a development overnight," host Noel Fielding told the other celebrity bakers. "Unfortunately, Big Narstie can't be with us today as he's a little bit unwell, but he will be replaced by another baker.
He added: "It's a seamless swap, don't worry."
The new replacement baker was revealed to be Sandi, joining the likes of Johnny Vegas, Olympian Katarina Johnson-Thompson and Labour MP Jess Phillips in the famed marquee.
Dubbed 'Little Narstie' by Noel, Sandi quipped: "I haven't cooked a sponge since domestic science O-level."
And while viewers were sad to see Big Narstie disappear from the tent so soon, Sandi proved to be a perfect replacement.
She stepped up to the task of creating a 'self-portrait' cake, but judges Paul Hollywood and Prue Leith gave Sandi a recipe for her bake to follow seeing as she was joining last minute.
Sandi exclaimed: "Two seasons of presenting and I've honestly learned nothing, except for how to pronounce 'ganache' with panache."
While she didn't win star baker, Sandi's cake was even good enough to earn a famous Hollywood Handshake. "I think it's a well-thought-through and well-baked cake," Paul smiled, with Prue adding: "I agree."
After throwing herself into the showstopper challenge, she explained: "The thing that I really learnt today was to throw yourselves into it, give it a go, raise some money for Stand Up To Cancer and you have a lovely end product as well."
We couldn't agree more, Sandi.
The Great Celebrity Bake Off continues on Tuesday, 26th March at 8pm on Channel 4. Click here to donate or find out more about Stand Up To Cancer's campaign.