Put the first 6 ingredients in a small sauce pan. Heat over low heat until the dates are slightly softened and the chocolate is melted.

Puree in a food processor until smooth. Blend in the vanilla. Add the nuts, if using, and blend until just incorporated.

Lightly spread a 8x8 baking pan with oil. Spread the fudge mixture out into the pan, patting or rolling as smooth as possible. Refrigerate for an hour or two.

Depending on the nut butter you use it might be sticky, if that is the case you can roll the fudge in cocoa butter or cut and separate the pieces to sit in the fridge for a few more hours until less sticky.