I thought I would update my original post with the results of this project even though I have blabbing about it all over the forums.
All in all, it turned out great!
I made my variation of Rose’s Yellow Butter Cake with lemon oil, zest and poppyseeds, split all the layers, brushed with lemon simple syrup, and filled with buttercream mixed with the Raspberry Puree, and frosted with Lemon Mousseline Buttercream.
There were certainly a few bumps along the way.
First, I had to rebake the 12” layers for the bottom tier because of a dumb mistake (lesson 1: always make sure you measure the space between the racks and that it is over 3” just shy of that and the cake can stick to the rack above it!)
Second, I tried to save a batch of mousseline buttercream that had not set properly. I used it crumb coat the cake ~ a mistake. I made 2 smaller size batches of replacement mousseline for the outer coating of frosting and piping (which came out perfectly!) but the funky soupy buttercream which was used to crumb coat the cake started melting through in spots whenever it sat out more than a few minutes (it was a warm day, but not that hot). I was determined to save the first buttercream batch because it had 2 cups of lemon curd I had made for the occasion earlier in the week and it was so difficult to see it go to waste.
I decided my creation needed to be babysat through the ceremony and cocktail hour ~ into the walk in fridge it went and I planned to stay and move the cake back to the cake table myself. Luckily this cake was for friends of mine and they had some people cancel at the last minute. They just invited me to stay for the rest of the reception, which was lovely. So whereas normally mousseline can stay out for up to days straight, mind had to be chilled until 1 hour per serving.
Enough of that.
The cake turned out perfectly besides that! It transported like a charm! The mousseline I took with me for piping was satiny and held up beautifully! It tasted amazing!
I was grateful to be served a slice of my cake and analyze as well as enjoy it. The mousseline (flavored with limoncello and freshly squeezed lemon juice; and the crumb coat had lemon curd) really does melt in your mouth and translate the flavors so purely to your mouth. Several people said it was the best cake (and or wedding cake) they had ever had and people were excited about the poppyseeds! For some reason, that was a huge hit. I think that the flavor and texture combo was perfect ~ some familiar, some unexpected, and it all worked well together.
Every slice evaporated.
You see some more pictures here
I am glad that they requested this cake and set me off on this project. I have learned so much and gotten a great signature cake under my belt. I look forward to continuing to tackle new recipes in The Cake Bible as well and The Bread Bible* and Pie & Pastry Bible. Between the books and these forums, I am essentially putting myself through a baking correspondence course of the highest order. You guys have been so incredibly helpful.
Thanks to everyone for their help and support.

Now that this is over I can dream up what I want my own wedding cake to be! (October 4)
Rachel
*I don’t have this one yet.
Click thumbnail to see full-size image