In a vanilla cake recipe that calls for four egg whites and four whole eggs, you should use a total of eight eggs. The recipe is asking for four egg whites and four whole eggs separately, so you'll need both types of eggs to make the cake.
The breakdown is as follows:
- 4 egg whites
- 4 whole eggs (egg yolks + egg whites)
Adding both the egg whites and the whole eggs together gives you a total of 8 eggs needed for the recipe. Make sure to follow the instructions and separate the egg whites from the yolks as required for the best results in your vanilla cake.