Preheat oven to 400°F. Place liners in a regular-sized muffin pan (or pans) to equal 24 muffins.
In a large bowl, whisk together the flour, sugar, cornstarch, baking soda, spices, and salt.
In a separate bowl, combine the water, vinegar, pumpkin, oil, and vanilla. Stir to combine. Pour into the bowl with the flour mixture. Stir until just combined. Do not overmix. Add a cup of chocolate chips and stir to combine (reserving a half cup to use as a topping for the muffins).
Use a cookie dough dispenser or ice cream scoop to dispense equal amounts of batter into prepared muffin pans. Top each muffin with a few from the remaining chocolate chips.
Bake for 18 to 20 minutes or until a toothpick inserted in the center of one of the muffins comes out clean or with only a few crumbs. To keep the muffins moist, do not overbake. Cool muffins in the pan 10 minutes before removing them to a wire rack to cool completely.
Store muffins in an airtight container. They're best when stored at room temperature where they will keep up to 4 days. They will keep in¼ the fridge for up to 7 days or they can be frozen where they will keep 2 to 3 months.