Okay, so I don't have eggs and I can't run to the supermarket tomorrow, but I would like to make brownies from the box. I heard that you can use greek plain yogurt as a sub for eggs, and we have a LOT of excess greek yogurt that will expire in a few days, so I was thinking of using that, but it is vanilla flavored. Is it still okay to use? I also heard that swapping water for milk will make the batter better, but I'm not sure if I should sub in both yogurt and milk or just the yogurt. Also, I was thinking of amping up the flavor with a bit of vanilla extract, but if there is vanilla in the yogurt and I use that, I don't know if I should. Any tips?