can i do the cake mix extender for choclate cake? if so, how. also, i need to fill an 8" 3" deep round and do a 2-layer 6 inch, will that be enough. i'm thinking maybe i should just do two cake mixes. any input would be great. thanks

I use the cake mix extender for chocolate cakes that I found on this site. I'm not sure how many cups of batter you would need to make the cakes you mentioned, but I got approx. 10-11 cups from the 1 mix & the following extender (It was enough to bake a 12 x 2 inch square:
prepare cake mix per box instructions & also add:
1 c. flour
1 c. sugar
2 c. yogurt (or sour cream)
1 tsp vanilla (or other flavour)
1 egg
1/3 tsp salt
If cake is chocolate I add 3 TBSP of cocoa powder also.

Then bake at 325.