Other than Fireball, What's the best spell for cooking?

You can only make one object. I could understand if it was a big pot of soup, but I don't see how this counts as one object.
Here's how I'd use Fabricate to cook:
Fabricate plate mail.
Sell the plate mail.
Use the money to hire a chef.
- This presents several problems.
  What is "one object"? A proper suit of platemail is like 30 objects, the helm is a different object to the breastplate, and that is a different object to the left sabaton. Such a ruling could cause a lot of table arguments.
  Why is "a banquet" different to "a suit of platemail" in this regard? They're both comprised of several smaller components that could individually be described as objects?
  The spell doesn't explicitly say "you can only make one object" it repeatedly, and irresponsibly careens wildly from using singular examples, and using plurals. The first line of the spell text is "You convert raw materials into products of the same material." (plural) It then gives examples of "a bridge, a rope, clothes" (singular, singular, plural).
  I don't see a sage advice on this issue specifically but Crawford has answered "can you make a full set of artisans tools with a casting of fabricate" with yes - and most sets of tools aren't "one object" either...
  Remember to check creative uses of your spells with your DM. Your DM is at risk and your DM can go down as well as up, and you may not get back all the DM that you put in.
  
  If it's on a single line on a chart in the PHB, it's one object.
- Your argument is that a banquet is multiple items and your solution is making plate mail?
  
  It really shouldn't be, but the game treats it as one. For example, the Cleric Forge's Channel Divinity blessing.
  You conduct an hour-long ritual that crafts a nonmagical item that must include some metal: a simple or martial weapon, a suit of armor, ten pieces of ammunition, a set of tools, or another metal object.
  This is more specific than the general rule
  For the purpose of these rules, an object is a discrete, inanimate item like a window, door, sword, book, table, chair, or stone, not a building or a vehicle that is composed of many other objects.
  So in the case of armor, it counts as one object even though it's not a discrete item. But unless there's something calling a feast one object, it follows these rules.
  If you allow a feast, what doesn't count as "one object"?
- The object is dinner
- I do love when someone jumps in to "well actually" all over people who are just having fun - and their assertions are just wrong.
  
  Yeah and using it to cook dinner is much less broken than using it to generate 1500 GP from the 5e commerce that is not a simulation of any actual economy.
  If I had a player use it for a narrative meal, I'd absolutely allow it, and if they were using it to just generate gold, I'd make them jump through hoops to find a buyer.

Need to light the campfire? Prestidigitation! Also works to extinguish it.
Dropped a spoon on the ground? Prestidigitation! It's clean again!
Lost the spoon? Prestidigitation! You have a new one for twelve seconds, long enough for a quick stir.
Forgot a spice and the flavor is off? Prestidigitation! Your meal now tastes exactly how you want it to.
Need to call the party to eat? Prestidigitation! You create a flare, the sound of a chime, or just spread the smell of cooked food around.
Left the food out too long and now it's cold? Prestidigitation! It's the perfect temperature again. Also works for chilling drinks (your booze hounds will thank you).
Post-meal cleanup? Done in under a minute no matter how messy the barbarian eats, thanks once again to prestidigitation.

Barbarian: PUNCH. If you hit the chicken enough times, eventually you'll impart enough energy to cook it.
- https://youtu.be/68L6JA_CnmU
  If you ever wondered how many time you'd actually need to
- Punch cow instead. It's safe to eat raw.

Ah man, this just made me remember how much I miss the daily Konsi comics.
- I wish I could draw faster, but this process takes a lot of steps, and I substitute my lack of raw talent with time spent.
  
  Sorry I didn't mean to sound demanding. You're doing awesome work and delivering it to us for free! I was just remembering how awesome that series was.
  
  Keep them coming as much as you'd like and can handle either way. We'll look forward to the next

That's a brilliant use for Fabricate! I'd totally allow it.

Reminder that WotC tried to retroactively revoke the OGL

You could always try curing your meat
- That's not what I meant!

Animate dead + purify food and drink. Pull off a spare rib whenever and wherever you need it.

Mirage Arcane. They may be eating twigs and leaf mulch, but they will enjoy it.
- You make terrain in an area up to 1 mile square look, sound, smell, and even feel like some other sort of terrain.
  No mention of taste. You'd better make it smell really good. Or just use Prestidigitation.
  
  You can make the argument taste is just extreme smell.
  
  This adds a whole new dimension to "chewing the furniture"
- Pathfinder has a spell called Allfood, makes literally anything into "food" (well, it's tasteless mush, but it is edible). Creative uses include: chewing through doors, literally eating important MacGuffins, and disarming opponents via CHOMP.

Hooray another chapter!
...aaaand now I'm hungry.

... Create Food and Water? 🤷🏻‍♂️
- That only creates bland food.
  
  Fireball only creates charcoal. I figure bland would be better than pure carbon 🤷🏻‍♂️

Heat metal!
How has nobody said this yet? Get that skillet hot!
- Fun fact, the hammer also does heat metal. Konsi uses it to make pancakes.
  
  The hammer? Who?
- The best camping spell. No need for a fire that might draw unwanted attention

I'd allow it.

I guess Heroes feast does not really count as cooking so...:
You could use wish and wish for the meal to be cooked perfectly
Mage hand is very helpful when you want to lift a hot pot or pan.
Since objects made by creation are real for the duration of the spell, you could create some food, it eat and even give your stomach time to... salvage the valuable parts before the spell ends
- The perfect diet food, maybe?
  I think that, generally speaking, food that's magically generated for a temporary period of time counts as "real" if you eat it - you get the nutrition from it. (c.f. Magnificent Mansion) - which raises interesting questions about the metaphysics of DnD.
  
  Depends on the amount work put into the magic systems lore from the DMs side. (I once wrote the ,,Theorie of magical trinity: Command, energy and will" and there's a lot of other work out in the internet as well)

Immediately thought of hero's feast, but fabricate works too

Animate Dead

Wall of fire.