I just bought two 8 inch, 2inch deep, cake pans. It says to fill 1/2 or 2/3 full, they say approximately 3 cups of batter each, but I have a box mix of Duncan Hines chocolate. I looked it up on the internet and it appears to only make 5 cups? So I'm thinking I need just a bit more, and I don't want to do two boxes, because I'll end up wasting some. So should I extend it with some sort of recipe?

How short will you be? Just add equal amounts of sugar and flour, plus some extra chocolate (grate bakers chocolate or use bakers powder).

I would also add about 1/4 mayo.

Here's a basic extender recipe you can use with basically any flavor of cake. It will fill two 8" pans (2" deep) perfectly, none wasted.

1 box mix
1 cup flour (for chocolate I use 3/4 flour amd 1/4 cocoa powder)
1 cup sugar
1 cup sourcream
4 eggs
water and oil called for on box (I use milk and butter)
vanilla(or flavor of choice)
1-4oz box flavored instant pudding

Or, you can use 2 mixes, make an extra 8" (or 2 6" cakes) and freeze them. No such thing as "wasted cake"!

I know this may be a dumb question but I never extended or doctored a recipe before. If you use milk and butter how much butter do you use? And do you add the pudding mix dry or prepared?

I am guessing that the added flour is self-rising? Cake flour or regular baking type? Thanks (sorry for dumb questions ).

I use all purpose flour, dry instant pudding and the same amount of melted butter as oil.

Awesome! Thank you so much!! Oh yes, I never thought of freezing a cake either before. lol I'll learn yet!

Thanks again!