Close up of the bands of colour. I used a butter cream filling, but also used lemon butter spread between the two layers. This started as a vanilla cake.
Complete cross section. Notice that the colours of the Rainbow are in order - Red, Orange, Yellow, Green, Blue, Violet. ( Yes, I missed out on Indigo. )
This piece was sliced off the top, to flatten the bottom layer. It shows how neatly aligned the rings were.