PREP: Preheat oven to 350 degrees F and line a baking sheet with a Silpat liner or parchment paper; you definitely need a liner for these cookies, because the dough gets sticky!
MIX: In a large bowl, add the entire box of the spice cake mix, the entire can of pumpkin puree, and 1 large egg. (Don't add any ingredients called for on the back of the spice cake mix.) If desired, add in a teaspoon of vanilla extract. With a hand mixer or a wooden spoon, mix until ingredients are combined. Don't over-mix the dough. Stir in 1 cup of the chocolate chips.
MEASURE: Using a 4-teaspoon measuring spoon and a small spoon, scoop out balls of dough and place them on the lined cookie sheet. Each ball of dough should be 4 teaspoons (1 tablespoon and 1 teaspoon). Use spoons to coax the mixture onto the tray -- this is a bit sticky and difficult! (See Note 2) Spread cookies at least 2 inches apart.
BAKE: Bake for 9-13 minutes. They should spring back slightly back when touched, and not look gooey or glossy on top. Repeat to bake all the cookies, for a yield of about 36 cookies.
FINISHING TOUCHES: Let cookies stand on the pan for 5 minutes. If desired, right out of the oven, sprinkle the remaining chocolate chips on the tops of your cookies. This is an optional step; if you don't want extra chocolate, don't add extra chips. Use a sharp metal spatula to remove the cookies from the pan to a cooling rack to finish cooling. Pro tip: if you love salty-sweet flavors, add a small sprinkle of Maldon sea salt flakes to the tops of these cookies (optional).
STORE: Store cookies at room temperature, uncovered. Avoid using an airtight container; cookies will get a little mushy/soft. These cookies are best the same day they're made, and they get a little soggy regardless of how they're stored.