Yup, regular butter from heavy cream. I make it in my nutribullet blender, but I think any blender works. Or of course by hand but I've never tried it by hand.
This is the thread from lipstick alley where I learned about it:
https://www.lipstickalley.com/threads/how-to-make-ethiopian-hair-butter-at-home.1280228/
It's been just this past year, pre pooing with butter and sealing after washes with shea butter that my daughter's hair finally looks long. I don't know if she's actually retaining more length, or if her shrinkage is less, but I'm use to her shrunken hair drawing up to between her ears and shoulders, now her shrinkage is apl.
I've never used edible butter on my own hair because my hair has been in two strands twists since easter, and I wash in my twists, and I'm not confident I'd be able to rinse the butter out of the twists well enough.