Preheat the oven to 180C/350F. Grease and line a 12-count muffin pan with muffin liners and set aside.
In a mixing bowl, add your dry ingredients and mix well. Add the wet ingredients and mix until just combined. Fold through the chocolate using a rubber spatula.
Distribute the batter evenly amongst the 12 muffin liners. Bake the muffins for 20-23 minutes, or until a skewer comes out mostly clean.
Remove the muffins from the oven and let them cool in the pan for 10 minutes, before carefully transferring them to a wire rack to cool completely.
Notes
TO STORE: Leftover muffins can be stored in the refrigerator, covered, for up to 2 weeks. TO FREEZE: Place the muffins in a ziplock bag and store them in the freezer for up to 6 months.