Preheat the oven to 350°F.
In a large bowl, combine the yellow cake mix, melted butter, and egg until well mixed. Press the mixture into the bottom of a 9x13 inch baking dish.
In another bowl, beat the cream cheese until creamy. Add the pumpkin puree, eggs, and vanilla extract and mix until well combined. Add the melted butter and powdered sugar and mix well.
Add the cinnamon, nutmeg, and allspice and mix until well combined.
Pour the mixture over the cake mix base and spread it evenly.
Bake for 50-55 minutes or until the cake is set in the center.
Remove from the oven and let cool before cutting into squares.