[General] to cook something up

Hello
Does the bold part means "even the baby should be able to invent something"?
I must mention that baby could cook but I don't think Erewhon is talking about cooking food here. it confused me.

“We’ll help you,” Violet said finally. “What do you want us to do?”
“We need you to sneak into the arboretum,”
Finn said. “You mentioned your mechanical abilities, Violet, and Klaus seems very well-read. All of the forbidden items we’ve scavenged over the years should come in very handy indeed.”
“Even the baby should be able to cook something up,” Erewhon said.
“But what do you mean?” Klaus asked. “What should we do with all the detritus?”
“We need weapons, of course,” Erewhon said in the darkness.


"The End," by Daniel Handler

Yes, it is an idiom meaning "to invent/plan something for a dishonest purpose".

tedmc said:

Yes, it is an idiom meaning "to invent/plan something [STRIKE]for a dishonest purpose[/STRIKE]".

Click to expand...

See above.

tedmc said:

Yes, it is an idiom meaning "to invent/plan something for a dishonest purpose".

Click to expand...

It doesn't need to be dishonest or sneaky. It just means to improvise a quick solution or activity, to create something on the fly, to produce something fast and with no fuss.

If you say "cook up a scheme," that does suggest something sly.