Preheat oven to 350°F and grease a 9×13-inch baking dish with butter or nonstick spray.
In a large bowl, beat eggs with an electric mixer until thick. Add sugar and vanilla and beat to combine.
In a separate bowl, whisk together melted butter, flour, cocoa, salt, coconut, and pecans. Add to egg mixture and stir until well combined.
Pour batter into prepared pan and bake until a toothpick inserted into the center comes out clean, 25-28 minutes.
Meanwhile, prepare the frosting:
In a clean bowl, stir together the melted butter and cocoa powder. Add vanilla and 2 cups of the powdered sugar and beat well.
Add half of the milk, followed by remaining 2 cups of powdered sugar. Beat until smooth, adding more milk to reach desired consistency if needed.
When cake is done, immediately remove from oven and spread marshmallow creme over the top. Spread frosting over marshmallow creme and use a spatula or knife to swirl them together. Enjoy!