In a large mixing bowl, whisk together pumpkin puree, milk, eggs, brown sugar, oil, and vanilla.
On top of wet ingredients, add flour, baking powder, baking soda, cinnamon, allspice, ginger, nutmeg, and salt. Gently toss dry ingredients together before stirring into wet ingredients. Stir until smooth, but don’t overmix. Fold in chocolate chips (see note).
Heat a griddle over medium heat. If desired, butter or oil the pan. Scoop batter by about 1/4-cup portions onto heated pan. Cook until bubbles appear and pancakes start to look dry around the edges, 3-4 minutes. Flip and cook for another 2-3 minutes or until golden brown and cooked through. Repeat with remaining batter. Serve immediately.
This is a fairly thick batter, so you may have to turn your heat down to medium-low if they are getting done too quickly on the outside and not cooking through to the middle.
If you want a more uniform distribution of chocolate chips, you can sprinkle them onto each pancake after you pour the batter on the griddle (before flipping).
If desired, you can use pumpkin pie spice if you have it on hand. Use 2 3/4 teaspoon pumpkin pie spice and omit the cinnamon, allspice, ginger, and nutmeg.
Store leftover pancakes in the refrigerator for up to four days. They also freeze well and can be kept frozen for up to two months. Keep pancakes separated by parchment paper so that they don't stick together.