I am planning to make an iphone cake for my birthday which is coming up. I will bake in a 13" x 9" cake tin and I was wondering whether I'll need anything such as a flower nail or heating core for even baking and which one you would choose if I do?

I've used both and I don't find that either work for me. I just always wrap my cakes with bake even strips and cut off any dome.

I use the nails all the time. I use 2 for that size of pan.

I have never used a flower nail , nor a heating core in any cakes. If i have a little dome, i use a serrated knife and cut it off. That is just me, many people use them. Been decorating 17 yrs, without either.

I use a flower nail. If there is a dome on the cake I place a cookie sheet on top of it and press down as soon as it comes out of the oven. This helps level the cake so I don't have to trim anything. Works great.

I've made 16 x 2 rounds without a heating core or flower nail. I simply do as Msulli or icer does and mine have come out fine.