Preheat the oven to 350˚F and line a muffin tin with 12 paper liners. Set aside.
In a large bowl, mix together the pumpkin puree, milk, oil and apple cider vinegar.
Add the sugar, vanilla extract, chocolate chips and mix well.
In a medium size bowl sift the flour, baking powder, and pumpkin spice. Add the salt and mix well.
Add the flour mixture, half a cup at a time, to the wet mixture. Gently mixing until all the flour is fully incorporated.
Using a ¼ cup measure, scoop out the batter and drop into the paper liners. Bake in the center of the oven for 25 to 30 minutes. Test with a wooden skewer to make sure the muffins are fully cooked in the center. If not just put back in the oven in 5-minute increments until cooked all the way through.
Remove from the oven when done and allow to cool for about 15 minutes in the tray. When cooler, remove from the tray and place on a wire rack to cool fully.