All this discussion regarding the cake comes down to asking your 15-year old selves this: Would it be a cool (enough) conclusion of this arc?
If the answer is no, come up with something that would make at least somewhat sense. The "SHs help make the cake" theory seems logical. But is it cool?
My own answer is no. BM does not deserve the cake / help from the SHs. She is too dangerous for her surroundings and has done so much evil in her life that she deserves Starvation Hell in Impel Down, nothing less.
As for the how, I would much rather see BM actually rampage and destroy half of her kingdom and 3/4 of her army by the time her own children manage to stop her (Pudding and Chiffon). They are a family and supposed to be able to deal with their internal affairs on their own. Requiring outside help would make them seem weak.
Like right now, they are doing an OK job - they split forces to destroy the SHs, Bege and Germa, while Pero miraculously managed to redirect BMs anger towards hunting down the SHs, which is a solid approach so far, tactically correct…but I wish they supported the most important task in this plan, and at the same time, the clearly weakest link, Pudding´s idea of baking the cake to snap BM out of her rampage.
Leaving the main job to Pudding, who has only a few moments ago failed to fulfill her role in the Germa bloodbath plan, screams negligence for me. To me it seems like they aren´t as concerned with BM killing them all after she´s done with SHs.
But I am personally enjoying the escape so far. It´s important for me to see that if the future PK (which for him equals absolute freedom) is running away from a scenario, that there is no other way to survive, and that getting out of BMs territory alive after the damage they have done is a feat in itself.
How?
Maybe Zeus is out of comission after that bolt+overdose or BM simply smashes him next chapter for disobeying. The SHs make it to the ship and a brawl to acquire Sunny ensues. Jimmy in water (or is it cream?) is a powerhouse, they would have to break all mirrors on the sip to prevent more forces coming in. Tankman+Sanji+Jimmy somehow manage to kick Katakuri out, back to the shore, the rest deal with Pero army.
After that, the escape by ship starts, with the help of Jimmy´s old buddies. Meanwile, BM loses it completely and goes full Hulk mode and destroys towns.
Crazy action-sequences of underwater, sky and ship battles and out-manuevering a blockade during the escape. Black Sails on "One Piece magic" crack.
Later, at the border of BM´s territory Katakuri & Co. have to make a tough call whether to continue pursuing the SHs or turn back and deal with BM´s rampage.
Either they lose their kingdom or let the SHs escape, vowing to take them down later.
Pudding and Chiffon manage to bake the cake in the end. Pudding helps Chiffon escape afterwards.
BM pirates are unable to instantly pursue the SHs because their forces and cities are in ruins.
The SHs are totally exhausted, Sanji utilizes his cooking recipes to bring them back to shape within the relatively short time-frame until they are back at Zou to pick up the boy.
By the end of the Totland arc, the SHs managed to
- infiltrate into the center of one of the Yonkou territory
- crash her beloved tea party
- destroy the super delicious cake that took weeks to create
- crush her plans to acquire Germa technology in a bloodbath
- where is the Tamatebako? It was surely those bastards!
- steal her precious portion of the road map to Raftel
- make it out of there alive
That´s basically BM´s utter defeat considering her getting what she wants is her #1 rule in her world.