Place all of the ingredients (EXCL. the dark chocolate) into a food processor and process for about 1 minute until thoroughly mixed and combined.
Take the food processor jug off the machine and stir through the dark chocolate chunks until evenly spread.
Spoon the mixture into the muffin tray (use muffin cases if desired for easy removal or grease the muffin tray if not using the cases). Continue to fill until each of the 12 holes has an even amount of mixture.
Place the muffin tray into a pre-heated oven at 180 degrees C for 15 minutes.
Check the muffins are cooked through by inserting a metal skewer and seeing that it comes out clean.
Leave the muffins to cool on a wire rack. Once cooled, serve or store in an airtight container for up to 3 days.
Notes
Brush with a little pure maple syrup before serving - optional