The celebs floured their surfaces and got kneading in a bid to impress Paul Hollywood and Prue Leith.
Comedian Matt Lucas was also on hand to offer support to the celebs - not that these four needed it, with each surprising the judges with their baking abilities.
Nevertheless, only one could come out on top and win Star Baker.
Here's everything you need to know.
Who won Star Baker on week two of the Great Celebrity Bake Off 2021?
It was a tough competition in the Bake Off tent this week.
For the first challenge, the contestants were asked to make deep filled tarts and minus a few interesting looking bakes, they all managed to pull it out the bag.
X-Men star James McAvoy opted for a raspberry and lemon meringue pie, which Prue said was better than the traditional bake.
Similarly, Kelly's Eton Mess tart went down a right treat, while Anne-Marie ended up clapping for herself after Paul congratulated her on her first baking attempt.
The judges even enjoyed Baddiel's chocolate and mandarin tart, although it could have done with another hour in the fridge to set.
Next up was the technical challenge which saw the contestants making cheese scones and a butter of their choice.
Although Paul loved the taste of his scones, Baddiel came last because his bakes didn't quite fit the brief.
Kelly followed behind him, while Anne-Marie came second. This put McAvoy in the lead, as they headed into the Showstopper round.
For the final challenge, the contestants were tasked with making marble cakes which represented them in animal form.
While Anne-Marie decided to make a cheeky monkey, Kelly went for a bear, and McAvoy chose a snow leopard in reference to his Dark Materials character.
Baddiel chose to make a cake of his cat instead, decorating it in what Paul described as a "rudimental" fashion. The taste was much better, however.
The same couldn't be said for Anne-Marie, though. She managed to nail the design, but her cake was slightly over bake, with Prue admitting it wasn't a pleasure to eat.
Kelly and McAvoy nailed their furry cake creations though, with the judges loving the Olympian's chocolate and chilli cake, and gushing over McAvoy's snow leopard.
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"For somebody who doesn't bake, that's very good!" Paul said.
In the end though only one contestant could be named Star Baker and the judges decided that James had earned the apron. "I think it must have been exceptionally tight and I feel fortunate," he said graciously.
The Great Celebrity Bake Off for Stand Up To Cancer is on Channel 4 on Tuesdays at 8pm. If you’re looking for more to watch, check out our TV Guide. For more news, visit our dedicated Entertainment hub.