In a sauce pot on medium/low heat pour in heavy cream
As cream begins to heat up pour in sweetener
Using a whisk give the cream a stir. Cream sould not be boiling or sticking at all. If so the heat is too high.
Gradually add in cocoa powder little by little making sure all powder prior is dissolved before add more. This will avoid lumps of chocolate in fudge.
After chocolate has dissolved remove from heat and allow it to rest about 10 minutes.
At this point add in cacao butter and whisk in to make sure it's fully combined becasue it will want to seperate.
Pour in parchment paper lined pan adn place in refrigerator or freezer for a few hours. The freezer will be quicker but the refridgerator will allow the fudge to set more properly.