In a large mixing bowl, whisk together the flour, sugar, baking powder, bicarbonate of soda, salt and the chocolate chips.
In a separate bowl or large jug, whisk together the eggs, yoghurt/sour cream until completely smooth. Now mix in the vanilla, maple syrup, and oil, followed by the melted butter and then the buttermilk.
Transfer the wet ingredients to the bowl of dry ingredients and mix until just combined - try not to over mix the batter at this point.
Cover the bowl with clingfilm and leave at room temperature for one hour. If you don't have time, you can bake the muffins straight away.
After the one hour resting time, now preheat the oven to 220°C / 200°C Fan / 425°F / Gas Mark 7. Line a muffin tin with 12 paper liners - I like using tulip muffin cases.
Gently run a spoon through the bowl of batter. You’ll notice the batter is very fluffy, so be careful not to disrupt this as you spoon out the batter. Just run the spoon through the bowl and pull out the batter. Don’t mix it around or bother it too much. Distribute the muffin batter between the muffin cases.
Top each muffin with extra chocolate chips, if you desire. I will never say no to more chocolate! Bake the muffins for 8 minutes. After 8 minutes baking, now turn the oven temperature down to 180°C / 160°C Fan / 350°F / Gas Mark 4. Continue baking the muffins for a further 10-15 minutes or until a cake tester when inserted in the centre a muffin comes out clean, without any uncooked batter attached.
Once baked, leave the muffins to cool for 10 minutes. The muffins are now ready to serve and enjoy!