I think at a pinch, a novice (samanera) could do the cooking.
But the samanera can't pop down to the local shops to buy it, because of the 10th precept:
Jatarupa-rajata-patiggahana veramani sikkhapadam samadiyami
I undertake the precept to refrain from accepting gold and silver (money).
As regards fully ordained monks using money to buy food and then cooking it, IMHO I believe it would be considered as a breach of the vinaya.
Money and monks. How often have I heard this come up in a forum.
And it usually results in someone trying to give a valid explanation as to why they think it is acceptable to bend the rules.
Anyway, Just my one baht's worth.