Clara Turns Eight: Mint Chip Ice Cream Cake

I'm always happy to accomodate requests from the guest of honor when I make a celebration cake. Thankfully, I've been lucky so far and no one has asked for anything unreasonable. When my friend's daughter Clara turned eight, she requested an ice cream birthday cake with vanilla cake and mint chip ice cream. I immediately said yes even though I've never made an ice cream cake before. I figured it couldn't be that difficult -- you just need a cake and some ice cream, and I know how to make both of those things.

As I thought more about the cake, I decided to also add a chocolate sauce component. I used Jeni Britton Bauer's "Lady Cake" and "Runny Chocolate Sauce" recipes, and a mint chocolate chip ice cream recipe from The New York Times

I made the ice cream mixture first. The recipe requires a lot of mint leaves (more than four ounces) and I couldn't find any mint at the farmers market. So I decided to get mint from Amazon Fresh (we have a physical store within walking distance of our house and I like buying my groceries in person), as they sell reasonably priced 3-ounce clamshell containers of organic spearmint. You steep the mint in heavy cream; strain out the mint; add sugar to the cream and bring it to a simmer; add in a tempered mixture of egg yolks and sugar; cook the mixture until it thickens; put it through a sieve; let it cool; and then chill it until cold. My custard had just a tinge of pale green color from the mint.

This mint chip ice cream isn't just mint-flavored ice cream with chocolate chips. It's mint-flavored ice cream with fresh mint-chocolate chips, something I've never seen before. To make the mint chips, you melt bittersweet chocolate and spread it out over a sheet of parchment paper; lay a single layer of mint leaves over half of the chocolate; and fold over the sheet of parchment paper to enclose the mint between two layers of chocolate. You chill the chocolate in the fridge to set and then chop it. While many of my chips remained intact with mint hidden inside, quite a few split open, exposing the mint.

I also baked the cake and made the chocolate sauce while the custard was chilling. The sauce is a mixture of water, sugar, and Dutch cocoa powder that you bring to a boil and then take off the heat before adding unsweetened chocolate. You are supposed to run it through a food processor until it's smooth and glossy; I used an immersion blender.

The Lady Cake is a yellow cake that you can make with cake flour, whole-wheat pastry flour, cornstarch, or grluten-free flour. I honestly had no idea that you could just make a cake with just cornstarch, but the headnote says that cornstarch creates a "killer fine texture, with tiny little holes in the crumb and a caramelized flakiness on top." I used cake flour because I wanted to stick with what I know. You cream softened butter with sugar until thick and pale; add the eggs and vanilla; and alternately add in the dry ingredients (cake flour, baking soda, baking powder, and salt) and sour cream. I baked the cake in a parchment-lined 9-inch and split it into two layers once it was cool.
I assembled the cake in an 8-inch cake ring and I trimmed the cake layers to fit into it. I placed one cake layer in the bottom of a the ring and spread on some runny chocolate sauce. Then I froze the ice cream in my ice cream maker, folding in the mint-chocolate chips at the end. There were so many mint-chocolate chips that I didn't use them all. I took ice cream directly from the ice cream maker -- while it was frozen but the consistency of soft-serve -- and spread it on top of the cake layer and chocolate sauce in the ring. Then I added the second cake layer, spread on more chocolate sauce, and added more ice cream. Finally, I added more chocolate sauce and mint-chocolate chips to top it off. I put the assembled cake in the freezer overnight.
The next day I delivered the cake and advised our friends that they should run a kitchen towel under hot water, wring it out, and wrap it around the cake ring to warm it up a little and help release the cake from the ring. It was apparently still quite a struggle, and in retrospect I probably should have lined the cake ring with acetate to make it easier to remove the cake. Regardless, I thought the cake looked terrific. 
The cake was fantastic. The biggest surprise to me was the ice cream. I absolutely loved it, but it was very herbaceous and Clara's sisters at first thought it was basil flavored. It definitely did have a basil character to it, so much so that for a moment I honestly wondered if someone at the Amazon produce warehouse had slipped some basil into my containers of mint. The flavor of basil does have a mint-like component, but I had never thought about mint tasting like basil. Maybe it was just the particular variety of spearmint I used, but whatever it was, the flavor of the ice cream was really unusual and memorable, in the best possible way. I'm delighted with the way this ice cream cake turned out!

Recipes: "Lady Cake" and "Runny Chocolate Sauce" from Jeni's Splendid Ice Cream Desserts by Jeni Britton Bauer; and "Mint Chocolate Chip Ice Cream" by David Carmichael and adapted by Melissa Clark, from The New York Times

Previous Cakes for Clara: