Decarboxylate cannabis by breaking it into small pieces and heating it on a baking sheet at 220–240°F for 30–40 minutes
Melt unsalted butter in a saucepan or double boiler over low heat
Add water to the butter if desired to help regulate temperature and reduce scorching
Add the decarboxylated cannabis to the melted butter
Keep the mixture on very low heat for 2–3 hours, stirring occasionally
Do not let the mixture boil
Strain the mixture through cheesecloth or a fine mesh strainer into a container
Press out the remaining liquid from the plant material
Let the butter cool and separate from any water
Remove the solid butter layer and discard the water
Store the cannabutter in an airtight container in the refrigerator or freezer