Thank you all.
We saw a picture of something similar on the internet, so I decided to try it for my wife's birthday. The picture seemed to be a more traditional bakery-type cake with a tight crumb, and blueberry jam filling, so it sliced much cleaner. I decided to go with a light sponge, so it's not as pretty inside, but the whole cake was nice and light and not as sweet.
Bake the sponge in sheet pans, then slice into 4" strips and roll up in towels to cool (think of a jelly roll). When it's cool, unroll and cover in raspberry jam, then roll all the strips end-to-end into one continuous roll. You actually have a short, fat, jelly roll standing up on end in the center of the cake. When you slice into it, you're slicing through all the layers of the roll, so it looks like vertical layers!
The top and bottom layers are just more sponge cake, but with chopped dark chocolate bits added. The pink layers are fresh raspberry buttercream. I covered the whole thing in a whipped cream/cream cheese frosting.
Except for the layer of pink buttercream, it was all very light, and not too sweet. It actually came out pretty good for a first attempt. Next time, I would make the cake strips narrower and the top layer thinner to bring the whole thing into a better proportion. And I'd lighten the buttercream. The strong raspberry flavor of it was great, but it was a bit too rich for the rest of the cake. Can you tell, I'm my own worst critic???
So, to answer the questions:
3 layers?
Woman
Home cook (I work in the ERP software industry, so I'm a bit of a geek)
Raspberry