Preheat your oven to 350°F (175°C). In a large bowl, mix the yellow cake mix, melted butter, and 1 of the eggs until well combined. Press this mixture into the bottom of a greased 9×13 inch baking dish to form the crust.

In another bowl, beat the cream cheese until smooth. Add in the remaining 2 eggs, powdered sugar, cocoa powder, and vanilla extract. Mix until fully combined and smooth. Gently fold in the chopped pecans.

Spread the filling over the crust in the baking dish. Bake in the preheated oven for about 40-45 minutes, until the filling is set and the top appears slightly cracked.

Allow the cake to cool before slicing into squares.