Spray a 9 X 13 baking pan with baking spray. Set aside.
Place cake mix, flour, and sugar into the bowl of stand mixer. Mix just until combined.
Add water, yogurt, egg whites, oil, and extracts.
Mix on low speed until combined.
Turn mixer to medium speed and mix for 2 minutes.
Pour into the prepared pan(s) and place in preheated 325°F oven.
Set timer for 35 minutes. If you begin to smell the cake before the timer goes off, check the cake by sticking a toothpick in the center. If it comes out clean or with just a few crumbs but no wet batter, the cake is done and it needs to be removed from the oven.
Once the timer goes off, and you have not removed the cake already because it was done, check the cake for doneness by using the toothpick method.
If the cake is not done after 35 minutes, continue cooking the cake and checking for doneness every 5 to 10 minutes, depending on how wet the toothpick was when testing the cake.
When the cake is done, remove from oven and cool completely before frosting.
Place butter and shortening in the bowl of a stand mixer.
Using the blade attachment, mix on medium-high for 5 minutes.
Add powdered sugar 2 cups at a time and mix on slow until all sugar is incorporated.
Mix milk, extracts, and salt in a small bowl.
With mixer turned off, add milk mixture to icing.
Turn mixer to slow and mix until incorporated.
Turn mixer to high and allow to run for 5 minutes.
Test icing for consistency. If you want a thinner icing, add milk 1 tablespoon at a time and mix for 1 minute.
DO NOT add ingredients listed on the box mix.
If using this pan for an important event, please do a test run with this recipe and cake pan sizes you intend to use before the big event.
Cake recipe can be doubled for larger pans, adjust the baking time.
36 cupcakes can be made with this recipe. Reduce baking time to 18 to 20 minutes.
This cake needs to be supported if stacking greater than 2 layers high.
Icing recipe will easily cover a 2 layer 8-inch cake, amounts can be halved if the cake is being served in a 9 X 13 pan.
Cook time listed does not include the cooling time between baking and icing.
You will get 6 1/2 cups to 7 cups of batter when using this recipe as stated.
Can be made in smaller round pans for layering, adjust the baking time. 6" - 35 to 40 minutes, 8" - 55 to 60 minutes, 10" - 65 to 75 minutes.
6" pans hold about 3 cups of batter, 8' pans hold about 5 cups of batter, 10" pans hold around 8 cups of batter. You may need to double this recipe and make multiple batches for large cakes.
Use a baking nail placed in the center of the cake for pans 10" and larger.