Hi I am going to make a spongebob sitting on top of a hamburger my question is I need to make a 10 inch cake just trying to figure out how to make the top part of the bun to be a dome shape of the top bun so it can be equvalent to the bottom part of the bun? Spongebob will be sitting on top of it! any answers would be helpful! Thank you.

If you are only planning on doing one layer for bottom and one for the top I would think the best option would be to just carve the cake into a dome shape. It would probably be easier to carve a dome shape if you did a 10" cake and stack a 9" on top of that then you have more to work with. You could also baking the top bun in a rounded pyrex or glass bowl that has a 10" diameter. Hope that helps! 

Ok thank you for the advice I like the 9 in on top of the 10in cake that will work and I will have enough cake to feed everyone!