Preheat oven to 350°F degrees.
Grease baking pan with butter thoroughly.
Mix cake mix, melted butter, one egg.
Press mixture into prepared baking pan.
Beat cream cheese until smooth and fluffy.
Add softened butter to cream cheese mixture.
Beat in remaining eggs one at time.
Mix in powdered sugar and vanilla extract.
Add cocoa powder for extra chocolate flavor.
Pour mixture over cake layer evenly.
Bake for 40-45 minutes until set.
Cool completely before cutting into squares.