Recipe and Photo Source: The Cannabist
"No denying that cannabutter is the, well, bread and butter of the cooking with cannabis process. Here's a great place to start for your cannabis cooking needs."
Follow the directions, and you will make the best butter your weed will allow. The truth is however, the butter is just as good as the weed you make it with. Some people like to make a mild butter and use it to spread on their toast in the morning or add a teaspoon or two to a baked potato. (If you go that potato route be sure to add some bacon bits and chopped scallion.) But seriously, the stronger the weed the stronger the butter, so plan accordingly.
To make cannabutter like a pro, heat should be applied to the cannabis first to fully activate the THC, a process known as decarboxylation. To decarb your cannabis, heat oven to 240 degrees. Place the plant material in a single layer on a baking sheet with sides. Bake for 40 minutes, turning the sheet a couple of times to ensure even heating. The cannabis will become dry and crumbly. Now you are ready to add it to your butter or oil.
In a medium saucepan bring a quart of water to a boil on the stove. You can vary the amounts, just be sure that the marijuana is always floating about 1 1/2 – 2 inches from the bottom of the pan. When the water is boiling place the butter in the pan and allow it to melt completely. My recipe uses 4 sticks of butter to every ounce of marijuana, so if you’re using a half ounce of weed that’s about 2 sticks of butter.
Once the butter has melted you can add the marijuana. Once the weed is added the heat should be turned down, very low, to barely a simmer. I usually let the weed cook for around three hours. You can tell it’s done when the top of the mix turns from really watery to glossy and thick.
While the cannabutter is cooking set up the bowl to hold the finished product. I like to use a heatproof bowl, and some people use a plastic food container. Place a double layer of cheesecloth over the top, and secure it with elastic, string or tape.
Strain the marijuana butter over the bowl, carefully trying not to spill. When the saucepan is empty, undo the twine, pick up the cheesecloth from all four sides and squeeze out all of the remaining butter.
Allow the cannabutter to cool for about an hour. Place in the fridge until the butter has risen to the top layer and is solid. The THC and other properties have attached to the butter, and you are just about there.
Run a knife around the edge and lift the butter off. Place upside down on your work surface and scrape off any of the cooking water. Your cannabutter is ready to roll. Enjoy!