In a large mixing bowl, stir together the cake mix, melted butter, vanilla, and eggs. Place the mixture into a 9x13-inch pan sprayed with cooking spray and tamp it down to make a bottom crust.
Filling
Mix the granulated sugar and 1 teaspoon of cinnamon in a small bowl. Sprinkle half of the mixture evenly over the prepared crust. Set the rest aside.
Next, use a mixer to mix together the cream cheese, 1 teaspoon of cinnamon, and the sweet potato butter. Add the melted butter and beat. Add the eggs and vanilla and mix until blended. Add the confectioner's sugar and beat until well mixed.
Pour the filling over the crust. Sprinkle the leftover sugar/cinnamon mixture evenly over it. Sprinkle the pecans on top.
Bake for 40 to 45 minutes or until golden brown. The center will be wiggly when it comes out of the oven. Cool and then cut into bars.
Notes
Sweet Potato Butter
Click here for a sweet potato source.1 1/2 cups of sweet potato butter is approximately a 13-ounce jar. Because sweet potato butter is sold in different jar sizes, I have used more or less than stated in this recipe with equally good results. The smallest amount to use would be about 9 ounces.