Preheat your oven to 350°F (175°C). Prepare a 9x13-inch baking pan by greasing it with cooking spray or butter.
Prepare the Chocolate Cake Base: In a large bowl, combine 1 box of chocolate cake mix, 1 large egg, and ½ cup melted unsalted butter. Mix until well combined. The batter will be thick.
Press the cake mixture into the bottom of the prepared pan. Use your hands or a spatula to spread it evenly.
Make the Gooey Filling: In a separate bowl, mix 8 oz of softened cream cheese with 1 cup of confectioners’ sugar using an electric mixer until smooth. Then add 2 large eggs and 1 teaspoon vanilla extract. Beat until everything is well combined and creamy.
Fold in the 1 cup of chopped pecans into the cream cheese mixture.
Pour the cream cheese mixture over the chocolate cake base. Use a spatula to spread it evenly over the top.
Bake in the preheated oven for 40-45 minutes. The cake should be set around the edges but still gooey in the center. A toothpick inserted in the center should come out with moist crumbs, not completely clean.
Let it cool in the pan for 10-15 minutes before slicing and serving. Serve warm or at room temperature for the best experience.