Just a little background my recipes are designed for the medical marijuana patient to deliver consistant amounts of relief per item so that the patient knows how much to eat to relieve their symptoms.
I personally prefer to make a giant batch of butter once a year, it is a messy project and I would rather have it on hand than have to make it everytime I want to use it.
Use high quality butter, you may be suprised how much water content varies from one brand to another.
Potency of butter varies tremendously depending upon the strain and portions of the plant used.
Powder your cannabis using a coffee grinder or blender, add equal amounts of butter and water and boil at a rolling boil for 2 hours. Using water allows some of the €œgreen bite€ to be lost into the water but not the THC which binds to the butter. Strain liquid into another pan equal or greater through a cheesecloth or coffee filter. Then let sit overnight. Butter will solidify and then can be ladled off the top. Set butter on low-med heat to evaporated any remaining water. Ladle into a regular muffin tin (check your tin) but this should roughly be the same as a 1/2 cup then it is easy to add to recipes later. Let solidify by placing in the freezer and then place in freezer bags or vacuum pack if possible, if you vacuum pack this will last years!
Unlike smoked Cannabis, the effects of the butter will appear more slowly and have much longer duration.
Personal preference: I use 20 lbs of butter and 4 paper grocery bags of leaf (this is for 2 patients). I use ALL leaves, male plants, fan leaves etc. This past year I blended all my matter in my VitaMix and turned 4 bags of leaf into 1 gallon ziploc full of powder. Using cheesecloth and a metal collander I strained the above material. I use a LARGE (giant really) stock pot for the process. Realise that you will lose some butter weight for 2 reasons, there will no longer be any water content in your butter and some butter will be left in your cannabis and cheesecloth.
Using a vacupak I have frozen this butter for over 2 years with no noticable effect, another way to store is to wrap each "block" in saran wrap and then place in freezer bags pressing out all the air you can. Air circulating around the butter is what will make it nasty in the freezer, it can get freezer burn like anything else you might freeze.