Preparation Steps:

• Step 1: Preheat Your Oven. Preheat your oven to 350°F (175°C). This ensures that your cake will bake evenly.
• Step 2: Prepare the Base. In a mixing bowl, combine the devil's food cake mix, 1 egg, and 8 tablespoons of melted butter. Mix until well combined. The mixture will be thick and crumbly. Press this mixture into the bottom of a greased 9x13 inch baking pan to form a crust.
• Step 3: Make the Filling. In another bowl, beat the softened cream cheese until smooth. Add in the Nutella, 3 eggs, vanilla, and 8 tablespoons of melted butter. Gradually mix in the powdered sugar until fully incorporated. The filling should be creamy and somewhat thick.
• Step 4: Assemble the Cake. Pour the Nutella filling over the crust in the baking pan. Spread it evenly with a spatula.
• Step 5: Bake. Bake in the preheated oven for 40-45 minutes. The edges should be set while the center remains slightly gooey. A toothpick inserted into the center should come out with some moist crumbs.
• Step 6: Cool and Serve. Allow the cake to cool in the pan for at least 15 minutes before slicing into squares. Serve warm or at room temperature, and enjoy the gooey goodness!