Preheat the oven to 350° F. Prepare a cookie sheet/half sheet pan (13"x17") that has sides on it, and spray it well with cooking spray making sure to spray the sides as well. Set aside for later.

In a large mixing bowl using an electric hand mixer, or use a stand mixer with the paddle attachment, beat the melted butter, sugar, pure pumpkin, and vanilla extract until combined and mixed well.

Add in the eggs and whole milk. Beat until just combined and incorporated.

Add the flour, baking soda, cinnamon, pumpkin pie spice, and salt. Beat on low speed, increasing speed as needed, until no flour pockets or streaks remain in the batter.

Stir in the bag of mini chocolate chips with a wooden spoon or spatula.* If wanted, reserve about ½ cup of the chocolate chips to sprinkle on top of the batter before baking.

Spread the batter into the prepared cookie sheet, using a spatula to smooth it out as best as you can. * The batter will create a thin layer, which is normal, as it cooks the batter will puff up and thicken.

If you reserved some chocolate chips, sprinkle those on top of the bars before baking.

Bake for 14-18 minutes or until a toothpick inserted into the center comes out clean. The edges will be golden brown and pulled away from the sides of the pan, and the middle should not look wet and shiny (usually means it's raw).

Let the pumpkin bars cool in the pan for at least 30 minutes before slicing into squares for serving.