Step 1: Preheat and Prepare: Preheat oven to 350F (175C). Grease and flour a 9x13 inch baking pan. This ensures the cake releases easily after baking.
Step 2: Combine Dry Ingredients: In a large mixing bowl, combine the chocolate cake mix and instant chocolate pudding mix. Whisk together to ensure there are no lumps and the ingredients are evenly distributed.
Step 3: Add Wet Ingredients: Add the vegetable oil, eggs, milk, and vanilla extract to the dry ingredients.
Step 4: Mix the Batter: Using an electric mixer, beat the ingredients together on low speed until just combined. Then, increase the speed to medium and beat for 2 minutes, until the batter is smooth and well-mixed. Avoid overmixing.
Step 5: Pour into Pan: Pour the batter into the prepared baking pan, spreading evenly with a spatula.
Step 6: Bake: Bake in the preheated oven for 30-35 minutes, or until a wooden skewer inserted into the center comes out with only a few moist crumbs attached.
Step 7: Cool: Remove the cake from the oven and let it cool in the pan for 10-15 minutes before inverting it onto a wire rack to cool completely.
Step 8: Frost (Optional): Once the cake is completely cool, frost with your favorite chocolate frosting or dust with powdered sugar. Add chocolate chips for a delicious final touch.
Optional Tips: For a richer flavor, substitute coffee for milk. To prevent sticking, line the baking pan with parchment paper. Consider adding a layer of chocolate ganache for an extra-decadent treat.