I'm making my first 9 x 13 " rectangle cake, and the only recipes I have are used in an 8x8 round cake. Do I need to make extra batter...should I double the recipe?

2 8 inch rounds equals the same amount of batter as a 9 x13
or 1 box mix if using a mix

I don't really have the answer you are looking for.. I always make more batter then I need, just in case. And then I bake and freeze what I don't use. Use the left over cake for decorating practice, or make cake balls.I'm sure you could find someone to take any extra desserts you have

1 box mix is appx 5 cups of batter and 1 mix is enough for a 9x13.

...is it gonna be a single or double layer??? Ya tortin' it?

double lawyer...well im going to torte it (if that means making one into two!).
i don't use a mix either...always from scratch

Cake Spackle Recipe

3-4 cups of cake crumbs
1/2-3/4 cups butercream

Mix all the ingredients to form a thick paste. If the paste is too stiff, add more buttercream to soften. I use to fill in between the cake and to bring the crack level. Let dry. Then, ice cake with regular buttercream. It's also used to fix cracks in cakes, too. Let it dry after applying it.

Whoops. Sorry. I had two tabs open and so I posted it in the wrong one.