Preheat the oven to 300°F. Line a 9x13 baking dish with parchment paper, set aside.
In a large bowl with an electric hand mixer mix together the yellow cake mix, melted butter, and 1 egg until combined.
Press into the bottom of the baking dish, set aside.
In a large bowl with an electric hand mixer add the remaining 2 eggs, cream cheese, and powdered sugar.
Mix until smooth.
Pour over the crust.
Bake until the top appears dry and it is crinkly. The crust along the edges will be lightly golden brown, 40-45 minutes.
Let the bars cool in the pan completely. Use the parchment paper to help you lift it out and cut it into bars. Add a dusting of powdered sugar if desired.
Notes
You can use any cake flavor that you'd like.
Extracts can be used in the cream cheese mixture to change up the flavor, see some suggestions above.
Other toppings can be used, see above for ideas.
This makes a large batch, but can be doubled.
These can be frozen, see above on how to do that.
Top with a variety of toppings, see some of my ideas above.