I’m pretty sure what I saw was a white cake mix, & it works really well. But I didn’t actually go to that link - someone was just noting what they were using for easy lemon bars. A lemon mix would make it that much more lemony!
Thanks! Either white or lemon mix sounds dandy. Have shared this with a friend but actually gave her the white mix when doing so. Wrote her again telling her about the lemon mix and in her words “I was going to use lemon anyway. She loves lemon. Must be why we get along so well :-)