Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking pan.
In a large bowl, mix the cake mix, milk, melted butter, and eggs until well combined. Pour the batter into the prepared pan.
Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Remove from the oven and let cool slightly.
Use the handle of a wooden spoon to poke holes all over the cake.
In a bowl, mix the sweetened condensed milk, caramel sauce, and chopped pecans. Pour the mixture over the warm cake, spreading it evenly to fill the holes.
Let the cake cool completely, then spread the whipped topping over the top. Sprinkle with toasted pecans and drizzle with extra caramel if desired.
Notes
Store the cake in the refrigerator for up to 3 days.