I decided to try and re-do my white zucchini cake with yellow zucchini, then cover it in gobs of chocolate frosting of course. The moisture and delicate flavor in zucchini always make cake amazingly moist!!
Heat oven to 350°F. Prepare two 8in baking pans.
In a stand mixer with paddle attachment, combine butter, sugar, and vanilla. Beat on medium speed for 30 seconds, then on high for 2-4 minutes. You are looking for a light and fluffy sugar mixture. Add egg whites and mix until just incorporated.
Remove from oven when an inserted toothpick is removed MOSTLY clean, a few crumbs are good. You do not want to overbake this cake.
Cool in pans about 15 minutes then invert onto a cooling rack.
Cool completely before frosting and stacking.
Make sure cake is cooled before stacking and adding frosting.