The enormous cake: assembly!

Now that the layers were made and frozen, and the frosting and fillings were ready, it was time for assembly!  My friend the mechanical engineer stopped by to help with structural supports (dowels are key) and I just went to town!

For inspiration, this is what McCormick Hall looks like from across the river:

Luckily, it's a lot of rectangles, and even better, the towers have the same aspect ratio as a 9x13 pan (yes, there was a lot of math and the original architectural plans involved). 

It helps to make a barrier out of frosting when adding the fillings, otherwise you end up with raspberries seeping out the sides...and no one wants to have a cake that is bleeding.  Not a great look.

The twins showed up to help!

My mechanical engineer, after her intense 60s makeover. 

The first bites!  And no, I don't joke around when it comes to chocolate mousse filling. 

To summarize the whole experience (and a special thank you to Smitten Kitchen's words of wisdom):

white and chocolate cakes (made a couple weekends before the event, tightly wrapped in saran wrap and foil and frozen)
time to bake cake: seven hours for each cake, done on separate days

raspberry filling - synthesized from many recipes, essentially a raspberry jam; 12 ounce bag raspberries : 1 tablespoon cornstarch : 1/4 cup sugar : 2 tablespoons lemon juice, cooked on medium for about 30 minutes and processed through a food mill

time to make a batch x8:  about two hours

chocolate ganache - yes, it's really just chocolate and water.  Incredible what heating and cooling and mixing can do when you do it at the right time, yes?   There are many "better" recipes out there, and ones I would prefer to use because they're easier but most of them contain gelatin, which would have made the cakes unfriendly to vegetarians, so I went simple on this.  If you can, make this the day of, we ended up having to re-whip it because it had hardened too much between Saturday and Sunday.
time to make a batch x8:  about two hours

dorie greenspan's vanilla swiss buttercream - a pain in the neck, but oh-so-tasty
time to make a batch x10:  (with two stand mixers) - seven hours (if you only have one stand mixer, it will take about an hour per batch, but you need to rest your mixer between each batch).  In hindsight, I probably would have made 11 or 12, maybe even 14 batches just to have a little extra around.

time to build cake:  4 hours labor (unwrap, set up, frost)

equipment used

square-sided 9x13 pans
parchment paper
saran wrap

aluminum foil
two large baking sheets (for helping cake-wrapping process)

wire cooling racks for cake
stock pot for making raspberry/chocolate filling

stick blender / stand mixer for mixing chocolate filling
food mill for removing seeds from raspberry filling

stand mixer for cake/frosting

innumerable bowls for preparing ingredients

storage containers for freezing raspberry filling and for storing frosting/chocolate

spatulas for frosting

frosting spreader

math!

cake cardboard

dowels

hack saw
plywood

food shopping list
2 - 5 lb bags flour
17 pounds butter (seriously)
44 cups of sugar (20 pounds)
one container cornstarch
5 dozen eggs
50 egg whites (4 pints egg whites)
16 cups yogurt
7.5 cups cocoa powder (645 grams)
one container baking soda
eight 12 ounce bags frozen raspberries
20 lemons
one container baking powder
10 pounds chocolate

total cost:  around $200 (Costco prices) - would be closer to $300 if buying things at Shaw's or Trader Joe's

time to plan:  three hours

time to bake/execute practice tower over the summer:  twenty hours

total time: 7+7+2+2+10+4+3 = 35 hours, give or take
(55 hours if you include the summer practice)