Double Chocolate Gooey Butter Cakes
["8 Tbsp. butter, melted (1 stick) plus 8 more Tbsp. melted (1 stick)", "1 pkg. chocolate cake mix (18.25 oz.)", "1 egg plus 2 eggs", "1 pkg. cream cheese (8 oz.), softened", "3 to 4 Tbsp. cocoa powder", "1 box powdered sugar (16 oz.)", "1 tsp. vanilla extract", "1 c. chopped nuts"]
["Preheat oven to 350\u00b0.", "Lightly grease 13 x 9-inch pan."]
["butter", "chocolate cake", "egg", "cream cheese", "cocoa powder", "powdered sugar", "vanilla extract", "nuts"]