What is the name of an old black and white thriller/horror movie about a woman who killed or cooked children?

I saw this movie about 15 years and I was very young so most of it is
a blur. I remember a woman (possibly old) trying to kill and cook
children. One scene I remember was someone sneaking through this woman
house and that person went upstairs and found a child's room that had
childrens' coffins in it. I know this isn't much to go off of, so I
apologize whole heartedly and appreciate any help!