Preheat your oven to 350°F and line a 13x9 baking dish with parchment paper.
In a big bowl, stir together the cake mix, ½ cup melted butter, and 1 egg until it turns into a soft dough.
Press that dough evenly into the bottom of your baking dish.
In another bowl, beat together the cream cheese, pumpkin pie spice, and vanilla until creamy.
Add in the pumpkin puree, the remaining ½ cup melted butter, and 3 eggs. Give it a good mix.
Mix in the powdered sugar until everything is smooth and dreamy.
Pour that pumpkin mixture over the crust layer.
Bake for 45 minutes — the center will still have a little jiggle.
Let it cool completely, then pop it in the fridge for an hour to set.