Line an 8-by-8-inch baking dish with parchment paper in 2 directions with a couple inches of parchment hanging off all 4 sides. There will be 2 layers of parchment to achieve this.

Add the butter to a saucepot or double boiler and heat over low heat until melted. Add the coconut milk and whisk to combine. Add the chocolate chips and stir frequently. Cook until all of the chocolate is melted and everything is well combined. Remove from the heat, add the vanilla, and whisk to combine.

Add the sifted sugar and cocoa powder to the bowl of a stand mixer and whisk to combine. Slowly drizzle in the chocolate mixture while combining everything on low speed with a paddle attachment. Fold in the walnuts until evenly dispersed. Transfer mixture to prepared baking dish.

Refrigerate for 8 hours or overnight. Remove from the refrigerator and use the overhanging parchment paper to lift the fudge up out of the baking dish and onto a cutting board. Cut fudge into bite-size 2-inch pieces.

Store in an airtight container for up to 5 days. Refrigerate for optimal texture and freshness.

If serving at a party, serve in small batches. The fudge will get softer sitting out at room temperature over time.