A Birthday Cake for Danny ... with Arrowroot

Week: 8
Ingredient: Arrowroot Starch
From: Martin’s, Harrisonburg, VA
Recipe: White Chocolate Blueberry Pecan Cake

This week (well, it’s Monday, so actually last week) was very busy, and I nearly forgot about finding something new and different to cook. In fact, when my mom and I decided on Wednesday that I would take care of making a cake for my brother’s birthday party on Sunday, all my culinary scheming became focused on Danny’s cake.

In my family you get to request any kind of cake (or pie or ???) you want for your birthday. So, like a good sister, I texted Danny:

I'm making cake. Tell me what you want or you get surprise!!

Danny replied:

i would like a cake that incorporates blueberries, pecans, and white chocolate, and no cream cheese! unless that's a bad culinary idea.... you're the expert!

Hmmm ... not a combination I would have picked. White chocolate can be a tricky ingredient for blending. In small amounts, it has a delicate flavor that can easily be overwhelmed by other flavors (like regular chocolate). In large amounts, it is so sweet and rich that it needs to be balanced out with something light, fresh, and/or tart (like lemon). When I thought through Danny’s idea, I decided it had merit. There would need to be lots of white chocolate if I wanted its flavor to come through along with the blueberries and pecans. However, the pecans would help cut the sweetness, and the blueberries would add freshness. Piece of cake! Insert groan at bad pun here.

My mind took off, exploring possibilities long before I had a chance to look for recipes. When I finally had time to sit down and do some research, I went straight for The Cake Bible,¹ which has become my go-to resource for all things Cake. (For those of you who are not familiar with Rose Levy Beranbaum’s masterpiece, I will just say that it is not for the casual baker. Read the reviews on Amazon if you want to understand more.) The first component of the cake was obvious: “White Chocolate Whisper Cake.” “White Chocolate Mousseline Buttercream” and “Winter Blueberry Topping” followed close behind. I toyed with the idea of incorporating pecans into the cake batter or using one of the nut cake recipes, but I could not decide on anything that satisfied me. So, I decided to toast the pecans and use them as a garnish. Still, I was missing something. The cake, buttercream, topping, and nuts were not going to come together in perfect balance in the four-layer pièce de résistance I was dreaming up. It needed more ... blueberry.

Enter blueberry curd. A curd is an intensely-flavored fruit spread, topping, or filling. Lemon curd is the canonical curd, but other fruits can be made into curd as well. A four layer cake would require three fillings. Two of blueberry curd and one of white chocolate buttercream would make a lovely balance. None of my trusted recipe sources had recipes for blueberry curd, but I figured I could improvise on another curd recipe. The plan was complete.

The first thing I made was the curd. When it was finished cooking, I set it aside to cool and moved on to the cake itself. I measured carefully (by weight, not volume), painstakingly followed the instructions, monitored the oven temperature closely, and rotated my cake layers midway through cooking. They came out looking perfectly golden and perfectly level. Fantastic, I thought. A short break, and then on to the buttercream.

It was not to be. Before I moved on to the buttercream, I realized something had gone horribly awry. The blueberry curd was not thickening, and the cake layers had both sunk in the middle. There was no way I could make a four-layer cake out of two half-sunken layers and runny filling. Quel dommage!

I was able to salvage the sunken cake layers. I trimmed them into two 1-inch layers. However, I considered the blueberry curd a complete loss, and it is still in my refrigerator (and will probably be used as a pancake topping).

The buttercream came together like a dream, and I used that (mixed with some pecans) to fill the layers. I frosted the (2-layer) cake with buttercream (sans pecans), and coated the sides of the cake with pecans. I piped a border around the top and bottom, and spooned the “Winter Blueberry Topping” (which also came together quite nicely) on top.

It was not the cake I had envisioned, but if I had not told the story, no one would have known anything was amiss. It was quite delicious. There is really nothing like a quality cake, and despite its flaws, this one was top notch (if I may say so myself). All the butter and white chocolate in the cake and icing gave it a wonderful melt-in-your-mouth quality (plus a little crunch from the pecans). The flavors of the white chocolate and blueberries complemented each other. Danny, you chose well!

Conclusion: I have not mentioned arrowroot starch at all so far. It kind of feels like I cheated. “Winter Blueberry Topping” called for arrowroot OR cornstarch. I really could have used cornstarch (which I always have on hand), but I needed a way to fit some new ingredient into this cake adventure; there was no time for something else. So, I used arrowroot. Maybe in a side-by-side comparison I could tell a difference between arrowroot-thickened and cornstarch-thickened blueberry topping, but in this stand-alone instance, all I can say is that it worked. That hardly seems like an adequate synopsis, so I will leave you with Rose Levy Beranbaum’s probably-based-on-actual-experience opinion that “arrowroot is preferable to cornstarch because it adds sparkle.”

¹Rose Levy Beranbaum, The Cake Bible (New York: HarperCollins Publishers Inc., 1988).