Surprise! There are kumquats in my cake rather than berries. This week’s Tuesdays with Dorie baking project gives the seasonal advantage to the bakers in the Southern hemisphere, so I decided to work with what is in season in my hemisphere.

photo by David Peterman
I made this cake by the book last summer for my sister’s birthday and it was spectacular. It tasted like a sophisticated, cloud-light, strawberry shortcake. The berry surprise hides inside a Chambord syrup soaked génoise cake that has been hollowed out and filled with fresh berries nestled in a cream cheese and whipped cream filling. A lid of génoise covers the berry surprise and the whole cake is covered in a blanket of whipped cream. The cake, filling, and whipped cream frosting are sweetened with a light hand to let the sweet ripe flavor of the berries really stand out.

photo by David Peterman
I decided to use buttercream frosting rather than whipped cream this time, thinking the heavier and sweeter nature of buttercream would stand up better to the bold tangy nature of kumquats, plus it pipes better and I really enjoy piping decorations on cakes. To prepare the kumquats I cut them in half and cooked them at a low boil for about 15 minutes in the left-over white wine and long pepper poaching liquid I had saved from poaching pears two weeks ago. Because I wanted to candy the kumquats I added a cup of sugar to the 1 ½ cups of poaching liquid to ensure they would be sweet enough. Short of having left over poaching liquid, you could just use a water sugar syrup and maybe toss in a few spices like cinnamon stick, cloves, mace blades or cardamom pods for good measure. In place of the Chambord syrup used in the berry version, I painted the génoise with the left over syrup the kumquats cooked it. After filling the cake with kumquats I then blended the remaining fruit with enough of the poaching syrup to make a thin glaze for the top and added honey to sweeten it a bit. I started with a pound of kumquats, but could have easily gotten by with half of that, as I had loads of glaze left over.

photo by David Peterman
The hollowed out construction of the cake allows for nice big pieces of fruit to be used in the filling. If this were a traditional layer cake the large pieces of fruit would create a structural disaster. Simply slicing off about 1/3 of the top of the cake, then hollowing out the other piece is all it takes. I found a grapefruit knife to be really effective for removing the inner cake. The one potential hiccup is if the center of the cake sinks a bit after baking. My cake sunk a bit this time, but I was able to salvage the situation by still cutting 1/3 of the top off the cake, which gave me a cake ring rather than a solid top. I then cut the middle out of the bottom layer by running a knife around the cake center at a 45 degree angle. This allowed me to remove the middle section as one solid disk that I then matched up with the ring to create a solid top. The remaining cake trimmings can be layered into a ring mold with fillings to create an individual dessert. Lucky for David, I managed to not eat the extra cake trimmings, so he got a special version of this cake made with a chocolate ganache filling.

photo by David Peterman

photo by David Peterman
I did add a little flavor to my cake in the form of ¼ teaspoon lemon zest (that I happily had on hand in the freezer) and ¼ teaspoon of ground juniper. It turns out that ¼ teaspoon wasn’t enough to actually detect the juniper and juniper isn’t what the cake needed. This cake was really delicious, a perfect cake for anyone who loves orange marmalade, but it needed a warm background flavor. I couldn’t quite decide what it needed so I sprinkled different things on bite after bite; finally determining the missing ingredient to be mace. Ironically, when I started making the cake I was going to use mace and even had it measured out, but then got the idea to try juniper. I think there is potential for juniper in a cake, just not in this cake. I would like to thank Mary Ann of Meet Me in the Kitchen for selecting a cake for us to make this week; I love making cakes! She has posted the recipe on her blog from Dorie Greenspan’s book, Baking: From My Home to Yours
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I will leave you with my standard buttercream recipe which is based on a Swiss meringue. It is light and creamy and not overly sweet. I save spare egg whites in the freezer and they are perfect for using in buttercream.
Buttercream Frosting
1 cup egg whites (about 6 large)
16 oz. granulated sugar
1lb 4 oz unsalted butter, room temperature
1 ½ teaspoon vanilla
½ teaspoon sea salt
Combine egg whites and sugar in the bowl of an electric mixer and place the bowl over a pan of simmering water. Whisk continuously and heat the mixture to 160 degrees F. Remove the bowl from the heat and set it in a larger bowl of cold tap water to cool it for 1-2 minutes, whisking continuously. The temperature should drop to 100-110 degrees F.
Transfer the bowl to the mixer and whip until the meringue forms stiff peaks and is cool to touch, about 75-80 degrees F. Cut the butter into tablespoon-size pieces and begin adding them one at a time to the meringue. Let each piece whip in before adding the next. Once all the butter is in, add the vanilla and salt. Continue to whip until the buttercream is thick and fluffy. Often as the meringue transforms into the buttercream it can take on a curdled texture. Keep whipping and it will smooth out. If it remains curdled and broken heat the bowl gently over a pan of simmering water while stirring constantly. Remove it from the heat as it becomes smooth and before the butter melts. Adding cold ingredients to the meringue is the most likely reason for a buttercream to break, so be sure the butter is soft.
Buttercream can be stored at room temperature for a day, or in the refrigerator for a week. It also freezes well and should be defrosted in the refrigerator and then brought to room temperature before using. If a frosted cake has been refrigerated, let it come to room temperature before serving.
Other flavors I enjoy: ½ teaspoon of vanilla with ½ teaspoon almond extract, or ¾ teaspoon almond extract and ½ teaspoon orange flower water, ½ teaspoon vanilla with ½ teaspoon rose water