Preheat oven to 425 degrees F and spray muffin tin with cooking spray. Set aside.
In a large mixing bowl, whisk the egg for 10 seconds. Add yogurt, oil, maple syrup, milk, vanilla, baking powder, baking soda, and whisk to combine.
Add flour and gently stir until well incorporated, batter will be thick. Do not over mix otherwise muffins will be tough.
Add chocolate chips and give a few more gentle stirs. Then, using an ice cream scoop, divide batter between 12 openings.
Bake for 7 minutes in preheated to 425 degrees F oven. Reduce heat to 375 degrees F (no need to wait for oven to cool off) and bake for another 10-11 minutes or until a toothpick inserted in the centre comes out clean.
Remove from the oven, let muffins cool for about 5 minutes and transfer to a cooling rack to cool off completely.
Notes
Store: Store in a cool dry place for up to 3-4 days.
Freeze: Freeze in an airtight container for up to 3 months. Thaw on the counter for 2-3 hours.