Set your oven to 350°F so it is fully hot by the time the batter is ready. Spray the 13 x 9-inch baking dish well with nonstick spray. I make sure to reach the corners, because that is where cakes love to stick.
Crack the eggs into a large bowl and beat them until they look smooth. Add the sugar and keep beating until the mixture is well combined. This step builds the base of the cake, so don't rush it.
With the mixer still running on low, pour in the vegetable oil slowly. Then add the vanilla extract and mix until everything looks glossy and blended. The batter should look silky with no streaks of oil left.
In a separate bowl, whisk the flour, baking powder, baking soda, pumpkin pie spice, cinnamon, and salt. Whisking spreads the leaveners and spices evenly. That means every slice tastes the same and rises the same.
Add the dry mixture to the wet mixture in small portions, alternating with the pumpkin puree. Mix gently until the batter is fully combined with no dry flour patches. Stop as soon as it looks smooth so the cake stays tender.
Add 1½ cups of chocolate chips to the batter. Use a spoon or spatula to fold them in gently until they are spread evenly. Folding by hand keeps the batter light and the chips well distributed.
Pour the batter into your prepared dish and spread it into an even layer. Smooth the top with the back of a spoon. If you like, scatter the extra ¼ cup of chips over the surface for a chocolatey crown.
Slide the pan into the oven and bake for 40 to 45 minutes. Check the cake by inserting a toothpick into the center. When it comes out clean, your cake is perfectly done.
Let the cake rest in the pan for 20 to 30 minutes after it leaves the oven. This helps it set, so the slices come out neat and the chocolate firms up slightly. Then cut, serve, and enjoy every bite