Preheat the oven to 425. Spray a 12-cup muffin tin with non-stick cooking spray and set aside.
In a large bowl, whisk together flour, baking powder, baking soda and salt.
In a medium bowl, whisk together brown sugar, Chobani, oil, eggs and vanilla. Add dry mixture to Chobani mixture and stir until nearly combined. If desired, gently fold in ¼ cup of the chocolate chips. Evenly divide batter among muffins cup--fill them all the way to the top!
Sprinkle tops of muffins with coarse sugar and the remaining ¼ cup chocolate chips.
Bake for 5 minutes at 425, and then reduce your oven temperature to 375. Bake for an additional 10 to 12 minutes, or until the center of the muffins resist light pressure.