Klay Thompson's relationship with Megan Thee Stallion got a big stamp of approval on Friday, 'cause his ex-NBA pops says the rapper is a "very nice lady" -- and one hell of a cook!!

The cams caught up with the two-time NBA champion Friday ... and he couldn't help but sing the praises of MTS and her chef skills.

Of course ... we asked what one of her great dishes was -- with Thompson shouting out her barbecue baked beans.

"Best I ever had in my life," he said.

The 71-year-old is so serious about her kitchen skills that he says she could open a cooking school!

"Nobody could ever cook as good as my mother, but man, Megan is a chef."

But the main question on everyone's mind is, could we see the Dallas Mavericks star dropping down to a knee and putting a ring on her finger?

"I don't know, it's up to them, gotta ask them that."

While it's their choice, it seems like Mr. Thompson wouldn't be opposed ... calling her a "very lovely lady."