2Beat together cake mix, cold water, eggs, oil, and 1 teaspoon vanilla in a large bowl with an electric mixer until very smooth, scraping down the sides of the bowl as needed. Pour batter into the prepared baking dish. Smooth the top, shake the dish, and tap lightly on the counter 2 or 3 times to eliminate air bubbles.
3Bake in the preheated oven until a toothpick inserted into the center of cake comes out clean, about 22 minutes. Let cake cool in the dish for at least 30 minutes. Poke holes all over cake with a bamboo skewer or the handle of a wooden spoon.
