What's a good weed:butter ratio for Cannabutter?

[MawMawPass]

I'm looking to make cannabutter for the first time and I only want to make enough for a batch of brownies. How much weed would you put in 1/2 cup of butter? Also, if anybody has any tips for making the cannabutter I'd appreciate it.

 

[blacken]

if you want one batch of bownies then here
Baking with Carnage & Blacken