Step 1: Preheat and Prepare: Preheat oven to 350F (175C). Grease and flour a 9x13 inch baking pan. This prevents the cake from sticking and ensures easy removal.
Step 2: Combine Wet Ingredients: In a large bowl, combine water, vegetable oil, and eggs. Whisk until well blended. Ensure there are no visible streaks of egg yolk.
Step 3: Add Dry Ingredients: Gradually add the cake mix to the wet ingredients, mixing on low speed until just combined. Avoid overmixing. Overmixing develops gluten, leading to a tough cake.
Step 4: Stir in Add-ins (Optional): If using, gently fold in vanilla extract, chocolate chips, sprinkles, or other desired add-ins. Distribute them evenly throughout the batter.
Step 5: Pour and Bake: Pour the batter into the prepared pan and spread evenly. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Baking time may vary depending on the oven.
Step 6: Cool and Serve: Let the cake cool in the pan for 10 minutes before inverting it onto a wire rack to cool completely. Frost as desired and serve.
For a richer flavor, substitute melted butter for vegetable oil. For a moister cake, add a small container of sour cream to the batter. Baking times may vary, so keep an eye on the cake.