With reference to RG class, I have a simplified step by step guide of how to cut out and a short video of how to cut and cream the cake. According to RG, you can either crumb coat and cover the whole cake with piping, which is what I did to dress up the doll or you can use a layer of cream to work as the base then pipe a little to dress up too. It's 2 options that we can work with. So, here you go.
Things to prepare:
8-9" Sponge, 3" height
6-7" Sponge, 3" height
**i use 8", 6" & 4"
1) Cut the different cakes into 2 layers and fill with fillings.
Stack the 2 cakes on top of each other
2) Use a small round cutter, use it as a guide and press onto the center of the cake on the top
Put the knife, 45degree to the 'marking' and cut slowly, turning the turntable slowly at the same time.
3) After cut out the dome, make some adjustments if you feel it's not curve or straight enough. Then do the creaming/crumb coat. Once done, cut a hole for the doll if you using the whole doll + legs or jus poke the half-body doll onto the top. You can start decorating now.