Preheat your oven to 350 degrees Fahrenheit. It’s essential to have the oven ready so that your cake can bake evenly. A well-preheated oven ensures a perfect rise.
Prepare your cake pans by greasing and flouring them. This step is crucial. It prevents your cake from sticking to the pan, making it easier to remove once baked. You can also use parchment paper for added security.
In a large mixing bowl, combine all the dry ingredients: the cake mix, flour, and pistachio pudding mix. Whisk them together so that they are evenly mixed. This will help in achieving a uniform texture in your cake.
Next, add the eggs, club soda or water, and oil to the dry ingredients. Using an electric mixer, beat the mixture on medium speed for about two minutes. Keep an eye on the batter; it should be smooth and slightly thickened.
Once blended, pour the batter into the greased and floured 9 x 13-inch pan (or divide it into two 9-inch round pans if you prefer a layered cake). Make sure it’s spread evenly.
Place the pan in the oven and bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean. The cake should be lightly golden on top. While it's baking, the aromas will fill your kitchen, making it hard to resist sneaking a taste.
After baking, carefully remove the cake from the oven and allow it to cool in the pan for about 10 minutes. This cooling time is essential; it allows the cake to set before transferring it to a wire rack.
Once cooled, you can frost the cake. In a deep bowl, pour in the milk. Add the Dream Whip and the second package of pistachio pudding mix. Using an electric mixer on low speed, mix for about 30 seconds, then gradually increase the speed until the mixture forms peaks.
Spread this fluffy frosting over the cooled cake. It should be light and airy, which is a perfect complement to the dense cake.
Finally, you can garnish with additional chopped nuts on top for added texture and flavor. Your Pistachio Cake is now ready to be served and enjoyed!