Preheat the oven to 350°F. Lightly coat a 9-by-13-inch baking dish with nonstick cooking spray.
Add the yellow cake mix, pumpkin purée, eggs, milk, vegetable oil, pumpkin pie spice and vanilla to a large mixing bowl.
Mix on low speed for 30 seconds. Increase the speed to medium and beat for 2 minutes, scraping down the sides of the bowl as needed.
Spread the cake batter evenly in the prepared baking dish.
In a separate bowl, beat the softened cream cheese until smooth.
Slowly beat in the melted butter.
Add the powdered sugar, maple syrup and vanilla. Beat until smooth and creamy. The mixture should be thick enough to hold its shape when dropped from a spoon.
Drop spoonfuls of the cream cheese mixture evenly over the cake batter.
Drag a butter knife through the batter a few times to create large swirls. Do not completely mix the cream cheese into the cake batter.
Sprinkle the butterscotch chips and pecans evenly over the top.
Bake for 50-55 minutes, or until the edges are set and the cake portions near the center no longer look wet. A toothpick inserted into a cake section, avoiding the cream cheese filling, should come out with a few moist crumbs.
Let the cake cool for at least 45 minutes before cutting. The center will continue to set as it cools.
Cover and refrigerate leftovers.
Notes
Soften the cream cheese first – Room-temperature cream cheese blends more smoothly and helps prevent little lumps in the filling.
Cool the melted butter slightly – Very hot butter can make the cream cheese mixture overly soft, so let it cool before slowly beating it in.
Keep the swirls large – A few passes with a butter knife are enough; overmixing will blend the filling into the batter instead of leaving creamy pockets.
Test the right spot for doneness – Insert the toothpick into a visible cake section because a cream cheese swirl will remain soft even when the cake is fully baked.
Give it time to cool – Cutting too soon can make the center look underdone. The cake firms considerably during the 45-minute cooling period.
Use pure pumpkin purée – Pumpkin pie filling contains added sugar and spices and can change both the sweetness and consistency of the batter.