Frequently asked questions

What is mochiko?

Mochiko is a sweet rice flour made from gluten-free short-grain rice. It adds a chewy and dense texture to baked goods like butter mochi. Find it at Asian grocery stores or online at bokksumarket.com. In this cake, sweet rice flour is balanced by a little all-purpose flour and baking powder to give the cake a pleasantly spongy yet chewy texture.

What can I do with the candied kumquat syrup?

Reserve the syrup from the candied kumquats for adding to cocktails, like the Citrus and Galliano Gin Fizz. The reserved syrup would also be great added to tea or lemonade.

Notes from the Food & Wine Test Kitchen

When making the frosting, it is super important that the butter and condensed milk are the same temperature. Assuming your sweetened condensed milk was stored at room temperature in the pantry, you need to make sure the butter is fully and completely at room temperature as well. (This is a little softer than you might think.) If the two ingredients are not the same temperature (or if you add the condensed milk too quickly), your frosting will break. But don't worry if that happens — it can be saved. You just need to warm it by whisking it over the very gentle heat of a double boiler and then beat the frosting to bring it back together.

Make ahead

The candied kumquats can be stored in syrup in an airtight container in the refrigerator for up to one week. Assembled cake can be stored in an airtight container at cool room temperature for up to two days.

Ingredients

Cake

1 cup mochiko (sweet rice flour) (such as Koda Farms) (about 5 ounces)
1/2 cup all-purpose flour (about 2 1/8 ounces)
1 1/4 teaspoons baking powder
1/2 teaspoon ground turmeric
1/2 teaspoon kosher salt
1/2 cup unsalted butter (4 ounces), melted and cooled, plus more for greasing
2 large eggs
1 (14-ounce) can sweetened condensed milk
3/4 cup heavy cream
1/4 cup yuzu juice or lemon juice
1 tablespoon grated lemon zest (from 2 lemons)

Candied Kumquats

1/2 cup thinly sliced kumquats (about 8 kumquats)
1/2 cup granulated sugar
1/2 cup water

Condensed Milk Buttercream

3/4 cup unsalted butter (6 ounces), softened
1 cup sweetened condensed milk, at room temperature
1 tablespoon grated lemon zest (from 2 lemons)
1/4 teaspoon ground turmeric
1/8 teaspoon kosher salt

Additional Ingredients

Bee pollen (optional) and fresh mint leaves, for garnish

Directions

Make the cake

Preheat oven to 350°F. Grease a 9-inch round cake pan with butter, and line bottom with parchment paper; set aside. Whisk together mochiko, all-purpose flour, baking powder, turmeric, and salt in a medium bowl; set aside.
Beat butter and eggs in bowl of a stand mixer fitted with the paddle attachment on medium-high speed until smooth and creamy, 1 to 2 minutes. Add sweetened condensed milk, and beat on medium speed until well combined, about 20 seconds. Add heavy cream, yuzu juice, and lemon zest, and beat until combined, about 15 seconds. With mixer running on low speed, gradually add flour mixture, beating until just incorporated. Increase speed to medium-high, and beat until smooth, about 10 seconds. Pour batter into prepared cake pan, and gently tap pan on work surface to release bubbles.
Bake in preheated oven until cake is golden brown and a wooden pick inserted in center comes out clean, 35 to 40 minutes. Let cake cool in pan 15 minutes. Invert cake onto a wire rack; let cool completely, about 2 hours
Make the candied kumquats

Bring kumquats, sugar, and 1/2 cup water to a boil in a small saucepan over medium-high, stirring occasionally. Reduce heat to medium; simmer, stirring occasionally, until liquid is reduced to a thick syrup and kumquats are tender, glossy, and slightly transparent, about 12 minutes. Pour mixture through a fine wire-mesh strainer over a small heatproof bowl; reserve syrup for another use, if desired. Place candied kumquats in a single layer on a parchment paper–lined baking sheet; discard any seeds. Let cool completely, about 15 minutes.
Make the condensed milk buttercream

Beat butter in bowl of a stand mixer fitted with the whisk attachment on high speed until fluffy and bright white, 6 to 8 minutes, stopping to scrape down sides of bowl as needed. Reduce speed to medium-low, and slowly add sweetened condensed milk, beating until well combined, 2 to 3 minutes. Add lemon zest, turmeric, and salt; beat on medium speed until frosting is thick and fluffy, about 1 minute.
Assemble the cake

Place cooled cake on a platter. Spread buttercream evenly over top of cake. Sprinkle with candied kumquats. Garnish with bee pollen, if using, and fresh mint leaves.