So, here’s the thing. It’s either cheap stoneware (yuck), or the original Corningware glass ceramic. I suspect it’s the former, but the listing indicates the latter, as well. 
I’m not sure how many types of materials CorningWare manufacturers, but this is name brand CorningWare if that helps.
It’s this item on Amazon:
https://www.amazon.com/CorningWare-10-Piece-Set-Ceramic-Bakeware/dp/B07V8VPMNT
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