Preheat the oven to 325°F (165°C).Grease and flour three 8-inch pans.
Combine the cake mix, milk, oil, eggs, and instant vanilla pudding mix in a large bowl.Beat the mixture with an electric mixer on low speed until blended.
Scrape down the sides of the bowl and continue to beat for 4 minutes on medium speed.Pour the batter into the prepared pans.Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 20 to 25 minutes.
Cool on a wire rack for 5 minutes, then run a table knife around the edges to loosen.Invert cakes carefully onto a cooling rack and let cool for about 30 minutes.