You don't want to cook the stems right in the food, where you actually eat them, because that, is gross. I did that once with cookies, and it was so nasty, I could barely choke 1 cookie down. Plus it didn't get me high.

12-13 grams of stems will give you very little cannabutter. Stems have a very small amount of THC on/in them, and using that amount to make butter will get one person barely stoned.

I suggest you make oil with them to get the most out of them. With that amount of stems, you might get just a gram of oil, even less.

Check out www.waytoomany.com under the Marijuana section, look for the title "Don't Throw Away Your Stems" and it's a video that shows how you can shake the kif from the stems. It's what I do sometimes.

I'll tell you though, I save stems in a container and this container holds about 14g's of stems. When I shake the kif from them, I get 1 bowl of kif from them , about 4 pipe rips, so you don't get that much.

Good luck.