In a mixing bowl, blend together all the wet ingredients with a hand mixier -pumpkin puree, milk, and apple cider vinegar.
In a large bowl, mix together all the dry ingredients (except for chocolate chips) - whole wheat flour, brown sugar, baking soda, powder, and pumpkin spice
Pour the wet ingredients mixture in the dry ingredients. Gently combine with a spatula. Fold in 2/3 of the chocoalte chips. Save the rest to add on top.
Line and grease a muffin pan. Use a medium cookie dough scooper to fill up each muffin cups close to the top.
Sprinkle the rest of the chocolate chips on top.
Bake 20 - 23 minutes or until a toothpick comes out clean after inserting in the middle of the muffin. If using a food thermometer, the internal temperature should reach around 200F.
Let it cool for 10 minutes on a cooling rack. Enjoy!