Preheat the oven to 400°F and grease a 12-cup muffin tin or line it with paper liners.

In a large bowl, whisk together the pumpkin puree, eggs, brown sugar, cane sugar, vegetable oil, milk, and vanilla.

In a medium bowl, whisk together the flour, pumpkin pie spice, baking powder, baking soda, and salt.

Add the dry ingredients to the wet ingredients and mix until just combined. Fold in the chocolate chips.

Evenly divide the batter among the prepared muffin cups, adding about a heaping 1/3 cup to each one. Top with more chocolate chips, if desired.

Bake the muffins for 15 to 20 minutes, or until the tops spring back to the touch and a toothpick inserted comes out with just a few crumbs attached. Let cool in the pan for 10 minutes before transferring to a wire rack to cool completely.