Melt the butter on low heat in a saucepan. Add the ground marijuana, and simmer on low heat for 45 minutes, stirring frequently.
Strain the butter into a glass dish with a tight-fitting lid. Push the back of a spoon against the plant matter and smash it against the strainer to squeeze out every drop of butter available. When you’re done, discard the plant matter.
You can then use your cannabutter immediatley or store it in the refrigerator for later use. Butter generally remains potent for about 2 weeks in the fridge and if properly stored in the freezer it can stay good for much longer. Potency will not fade but butter does go rancid eventually.
If you want to make more then a 1/2 cup at a time you can easily scale this recipe by using 4 sticks of butter and 1 oz of marijuana. You will also need to increase the simmer time to up to 1hr.