Puree avocado in food processor or blender until smooth. Place into large bowl.
Melt dark chocolate. Add brown sugar to melted chocolate and blend in avocado puree, almond extract and cocoa. Mix until well combined. Place the chocolate mixture into the refrigerator until it hardens.
Remove from refrigerator.
Line a sheet pan with parchment paper. Roll the chocolate into small balls, about 1-inch diameter.Roll truffles in chopped pistachios, cocoa powder or powdered sugar.Place onto sheet pan; refrigerate until firm.
Store in a covered container in the refrigerator until ready to serve.