OK I just made some brownies last week and they kicked my ass (I am a serious smoker so that means something.) I used one half ounce of commercial weed with one stick of butter. Bring the butter to a boil and simply break up the weed and throw it in. Simmer it on medium-low heat for at least twenty minutes, stirring occasionally so that the weed doesn't burn. Then use a thin strainer to seperate the weed and butter. The butter will look almost black and it smells pretty bad when you do it. You can cool the butter but what I usually do is just throw it in the brownie mix and into the oven it goes.
FYI - that one stick is enough for an entire batch of brownies. In order to enjoy a body high you really only need one (large) brownie. Of course I ate two and passed the fuck out for the rest of the evening. Then of course I got up and did it again. One batch should work, but I would make two for a take home party favor.