Diamond Head: Hubby's Birthday Cake!

 I wanted to bake a special cake for my husband's birthday celebration a few days ago and I knew that the Diamond Head cake from the book Extraordinary Cakes would be perfect for this occasion.  Since my hubby loves Mauna Loa Macadamia Chocolates, I was certain that he would love the Hawaiian-inspired flavors of this cake as well.   I also happen to love this chocolate-macadamia combo so I was really looking forward to having a slice of this cake all to myself.  I also found it hard to resist not licking my fingers and baking utensils after making the individual components most especially after I made the ganache, vanilla bean custard and macadamia brittle!  :-)  Actually, the three components on their own already make for a very satisfying treat.

Like the Viking cake I made for my Mom's birthday last month (which also happens to be from the same book), the Diamond Head is at least a 2-day production because of the many steps involved and the mandatory lengthy freeze required after the cake is assembled so I had to do some planning beforehand.  It was a good thing that the author gave the shelf life of each component so I knew which ones I could make days in advance and which steps I had to do no longer than an hour prior to assembling the cake.  My schedule went like this:

Day 1 -- Made the Bittersweet Chocolate Genoise, Simple Rum Syrup, Semisweet Chocolate Ganache and then toasted some macadamia nuts which will be used the following day.  Once the genoise was at room temperature, I covered the top of the pan in plastic wrap and left it at room temperature overnight.  I also covered the container of the rum syrup and placed it in the fridge.  Before placing the ganache in the fridge, I placed 1 3/4 cups of it in a separate container which will stay in the fridge for much longer as this will be used for the decorating portion of the cake.   

Day 2 AM -- Brought the ganache (not the 1 3/4 cups) and the simple syrup out of the fridge.  Made the Vanilla Bean Custard which had to be refrigerated for at least 2 hours before the whipped cream is folded in.  Looking back, this step could have been done on day 1.  I then whipped some cream then covered the bowl and set it aside in the fridge until needed.  Since I was assembling the cake days before decorating the cake, I only made half of the macadamia brittle as the recipe's portions include the brittle that will be used for the decor which may turn sticky if made too early.  I also ground some of the toasted macadamia nuts that will be sprinkled atop each layer of custard along with the brittle. 

Day 2 PM -- Prepared my tools and ingredients for assembly -- lined a loose bottom 10 x 3 round cake pan with a 10-inch cake board, brought out my piping bag and 1/2-inch round tip and ground the macadamia brittle in a food processor.   I then leveled the top of the chocolate genoise with a long serrated knife and sliced it into 3 equal layers.  I placed one layer on the bottom of the pan then brushed it with about 2/3 cup simple syrup. I then spread 1/3 of the ganache on top of the syrup-soaked cake layer.  By this time, the vanilla bean custard was already chilled enough so I folded in a portion of the whipped cream and spread half of it on top of the cake layer.  I then sprinkled half of the macadamia brittle and half of the ground macadamia nuts over it.  I put half of the remaining cream inside the piping bag and piped in the whipped cream over the nuts circularly from the center all the way to the sides.  The layering is done again in the same order as before finishing with a thin layer of the ganache on top.  I wrapped the entire pan tightly with plastic wrap and placed it inside the freezer.  At this point the cake can stay inside the freezer for weeks but it only stayed there for about 3 days before I brought it out for decorating.  

Day 3 (Decorating Day) -- This should be done the day before serving as the cake needs some time to thaw in the fridge.  I found un-molding the cake from the pan to be the trickiest part especially that it was frozen solid.  The author suggested using a blow drier to warm the sides of the pan in order to loosen the cake from the edges but I was too lazy to bother with this LOL.  Instead, I just used a long metal spatula dipped in very hot water and then wiped before inserting it in between the cake and the sides of the pan.  It worked pretty well except for a few parts where the spatula sliced off some of the cake parts but thankfully, I was able to put back some of the pieces with the warm spatula.  Oh and prior to un-molding the cake I brought out the 1 3/4 cups chocolate ganache so it would soften a bit and then made some more ganache using about 6 ounces of chocolate which will then be coated on the top and sides of the pan.   I also made the remaining macadamia brittle for coating the sides of the cake which ended up being such a nightmare for me.

The layers

Well, making the Macadamia Brittle became a nightmare because I made so many batches where the sugar ended up crystallizing instead of caramelizing thus wasting so much of these expensive nuts :-(  The first batch I made (the one I used for the layers) turned out perfectly crunchy and caramelized so I never thought that  I would encounter such problems making the next batch.  I  don't know if it's because of the constant stirring I made even before the sugar was dissolved (the recipe never gave any hints that this could happen) but I'm just thankful that adding a little corn syrup (about a tablespoon) to the sugar mixture prevented the last batch from crystallizing so I was able to finish the cake in time!  Phew!  Really, my heart was racing the whole time.

The scene that made all of my efforts worthwhile

This was the only dessert we served during the party and it was more than enough for our guests.  I'm happy to say that hubby and everyone else loved the cake!  I myself found it really delicious and I loved how the vanilla bean custard and whipped cream balanced out the richness of the chocolate layers.  I also loved the flavor, sweetness, and crunch that the macadamia brittle contributed to the otherwise creamy and slightly bitter layers of custard and chocolate.

This is a really HUGE cake and it even turned out bigger and taller than what was described in the recipe going above the 3" sides by about an inch more.  For anyone looking into making this, it's probably a good idea to only make about 2/3 of the vanilla bean custard to prevent the cake from getting too high.