Using a stand mixer with a whisk attachment, beat the eggs,sugar and vanilla on medium high speed for about 3-5 minutes. Beat until it becomes pale, fluffy and doubled in size. Turn mixer to medium speed and SLOWLY add the cooled butter to the egg/sugar mixture. *If you add it all at once you will deflate all the air you whipped into the eggs and sugar. Add the dry ingredients and beat until JUST combined (don’t over mix). Pour batter into prepared baking dish and bake for about 20-25 minutes. Check at 20 minutes, you’ll know it’s done when inserted toothpick comes out clean.