Ensure the unsalted butter is at room temperature for easy mixing.

In a mixing bowl, combine the softened butter, heavy cream, unsweetened cocoa powder, and vanilla extract.

Use an electric mixer to blend the ingredients until the mixture is smooth and creamy.

Taste the mixture and, if desired, add a pinch of sea salt to enhance the flavor.

Line a small baking dish or container with parchment paper for easy removal.

Pour the fudge mixture into the prepared dish, spreading it evenly with a spatula.

Place the dish in the refrigerator and allow the fudge to set for at least 1 hour, or until firm.

Once set, remove the fudge from the dish using the parchment paper.

Cut into 12 equal pieces.

Store any leftovers in an airtight container in the refrigerator.