Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking pan to prevent sticking.
Prepare the cake batter by combining the yellow cake mix, water, oil, and eggs according to package directions. Mix until smooth.
Pour batter into the greased pan and bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean.
Let the cake cool for about 10 minutes after baking.
Using the handle of a wooden spoon, poke holes evenly across the surface of the warm cake.
In a saucepan over medium heat, combine caramel sauce, sweetened condensed milk, and chopped pecans. Stir until smooth and heated through.
Pour the warm caramel mixture evenly over the cake, letting it soak into the holes.
In a bowl, combine whipped topping, powdered sugar, and melted butter. Stir until smooth.
Spread the whipped topping evenly over the cake.
Sprinkle brown sugar and extra chopped pecans on top for garnish.
Refrigerate for at least 1 hour before serving to let flavors meld.
