Doubling a PB cake mix
I'd like to double my cake mix (yellow) to make a ton of those yummie Boston Cream mini pies for a picnic. Don't know if I need to change am'ts of water, eggs or oil. I remember using Duncan Hines for 1/2 sheet b-day cakes and the baking time and ingredient hints were on the inside of the box for the changes. Don't want to mess this up, it's for a big picnic and my reputation's on the line as a dessert maker