It sounded strange to me at first, too, but I have both heard and used "do" in this sense (I am Australian but I suspect it is used in other countries too).
I might say "do a roast" meaning to roast meat and vegetables in the oven, with the suggestion I will serve it and eat with friends and/or family. "Do a casserole" also sounds natural to me.
Note that this is colloquial usage and I would not expect every native speaker to be familiar with this form, so I am interested to hear if other native speakers have encountered this use.
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