I made chocolate pudding & a small corner of the pan burnt. Is it ruined? How can I tell?
The only way to really know is to taste it. If you acted quickly you could possibly save the pudding but burnt flavor permeates pretty fast. I have had pudding stick before and it's been usable, I guess it depends just how badly burnt it is.
Very likely, it is NOT ruined. A bit of burnt as you describe it, might even add a smoky note to your pudding.
Generally...when I've burnt a pastry cream, pudding, lemon curd, custard, etc....I just pitch it and start over. But as sdebrango put it...the only way to know for sure is to taste it.