In a large mixing bowl, whisk together the dry ingredients (flour, baking soda, baking powder, salt and pumpkin spice).
Add chocolate chunks and stir in until coated.
In another mixing bowl, mix together the wet ingredients (pumpkin puree, oil, yogurt, vanilla and eggs). Add sugar and mix well.
Stir in the wet ingredients into the dry ingredients. Mix only until combined. Do not overmix.
Divide the batter among muffins cups.
Bake muffins for 5 minutes. Without opening the oven, lower the temperature to 375 degrees F and bake muffins for 12 to 15 minutes longer OR until the toothpick inserted in the center of each muffin comes out clean.
Cool the muffins in the pan for 10 minutes, then remove from the pan onto a cooling rack or wooden board.
Notes
To freeze: wrap tightly in plastic wrap, place in a ziploc bag and freeze for up to 3 months.