Preheat your oven to 325°F (165°C). Grease and flour three 8-inch pans.
In a large bowl, combine the cake mix, milk, oil, eggs, and instant vanilla pudding mix. Beat with an electric mixer on low speed until blended. Scrape down the sides of the bowl, then beat for an additional 4 minutes on medium speed.
Pour the batter evenly into the prepared pans. Bake in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool on a wire rack for 5 minutes. Run a table knife around the edges to loosen, then invert the cakes onto the cooling rack and let them cool completely, about 30 minutes.
In a large bowl, beat the cream cheese, confectioners' sugar, and white sugar until smooth. Fold in the whipped topping, pecans, and chopped chocolate bars.
Spread frosting on top of the first cake layer, then stack the second layer on top and frost. Repeat with the third layer, then frost the top and sides of the entire cake.
