Prepare an 8x8 square pan by greasing it or lining with parchment paper.
First, we need to make the sweetened condensed coconut milk. In a pot on medium heat, bring the coconut milk and the sugar to a boil. Keep a close eye on it so it doesn't boil over.
Reduce heat to medium-low and simmer for 40-45 minutes (until liquid is reduced by about half.) Whisk every 5 minutes or so.
Remove from the heat and stir in the vegan butter and vanilla extract. Then, stir in the chocolate chips until melted.
Pour into the pan. Let set in the freezer for at least 3 hours, or until hardened.
Cut into squares. Store in an airtight container in the freezer.
Notes
Optional: Add 1 cup of chopped nuts
The coconut milk will be used to make about 14-16 ounces of vegan sweetened condensed milk. There are storebought versions available, like Nature's Charm, that I have found on Amazon and at Whole Foods. If you get storebought, heat it until it just begins to simmer, remove from the heat, and proceed with stirring in the remaining ingredients.
This fudge will get really soft at room temperature. Storing it in the freezer will allow the fudge to stay solid enough to hold onto but soft enough to bite into.
I recommend storing in the freezer for up to 1 month - it will still be good after this time period, but I have found it gets "freezer burnt" easily.