Remember how I was done with baking?

Hahahahaha. Have I met me?

Ironically, it was that very cake recipe that lured me back into the kitchen! It’s just so, so good. So I got in the mood to make a layer cake, and of course, it’s stone fruit season so plums got involved.

Actually, this cake is full of familiar recipes! There’s the white mountain cake base, along with Stella’s Marshmallow Buttercream to go with, which I’ve never written about here but have shared on Instagram (one of my crazier moments!). The great thing about that frosting is that, while it takes a little more patience and time than other frostings, it doesn’t have the eggy taste that swiss meringue buttercream can sometimes have, and it can hold a good amount of liquid flavorings, meaning it’s infinitely adaptable. And the liquid I added was a plum caramel, from the same base recipe I used on a tart way back in 2017.

The plum caramel is really special. Adding in the plum puree instead of cream doesn’t make the end result taste especially like caramel, but gives the sweetened fruit a depth of flavor that just adds a little something more. The ginger gives everything just a little more zing. It’s perfect paired with the sweeter frosting here, and the plain vanilla of the cake lets the plums shine through as the star. Plus, how pretty is that pink?

This cake was a good reminder of how to find calmness in the kitchen, but also to just remain calm in the kitchen! It is a project, for sure, with all the various components, but I was not thinking of the news or anything, which was a nice break. I did, however, unfortunately decide to make a cake, and more specifically, buttercream in a heatwave, so my initial finished frosting was soup, basically. But I did not panic! Butter, as always, will firm up when it’s cold. My kitchen was sweltering from having the oven on, but I still have a fridge, so my buttercream got some time in the AC I was wishing for, and all turned out well.

White Cake with Plum & Ginger Caramel and Plum Buttercream

Adapted from Stella Parks’ White Mountain Cake and Marshmallow Buttercream

For the buttercream:

• 1 1/8 tsp powdered gelatin (1/2 envelope)

• 2 tbs cool water

• 1/2 tbs vanilla

• 3/8 cup (3 oz) water

• 1/4 cup + 3 tbs corn syrup

• 1 cup sugar

• 1/4 tsp kosher salt

• 2 1/2 sticks unsalted butter, room temp

• 1/4 cup plum & ginger caramel, recipe below

For the plum & ginger caramel (adapted from Food52):

• 3/4 lb ripe, red plums, pitted and cut into wedges

• 1 lbs lemon juice

• 1 inch ginger, peeled and minced

• 1/2 vanilla bean

• 3/4 cup sugar

For the cake:

• 2 cups bleached cake flour

• 1 stick unsalted butter, room temperature

• 1/3 cup coconut oil, room temperature

• 1 cup plus 2 tbs sugar

• 1 1/4 tsp baking powder

• 1/2 tsp baking soda

• 3/8 tsp kosher salt

• 4 egg whites, room temperature

• 1 tbs vanilla

• 1 cup buttermilk, room temperature

1. Make the marshmallow buttercream base: mix the gelatin powder, 2 tbs water and vanilla in a small bowl and set aside to bloom. In a pot over medium heat, combine the 3/8 cup water, corn syrup, sugar and salt. Stir with a fork until it bubbles, about 5 minutes, and then turn up the heat to medium-high. Let sit on the heat without stirring until the temperature reaches 250 degrees (see note).

2. Transfer the sugar syrup to the bowl of a stand mixer, scraping out of the pot (be careful!). Let cool to 212 degrees, then add the bloomed gelatin. Using the whisk attachment, stir on low speed until the gelatin is fully melted into the syrup, then increase speed to medium high and whip the syrup until tripled in volume and thick, snowy marshmallow fluff, and the mixture starts to cling in a ball shape around the whisk. Scrape this mixture into a well greased 2-cup container and cover (grease the lid!) and set aside at room temperature for at least 2 hours.

3. While marshmallow base is resting, make the caramel and the cake: add the plum wedges, lemon juice, and ginger to a blender and puree until very smooth. The plums should be ripe enough that no extra water is needed. Cut the vanilla bean in half lengthwise and scrape out the seeds.To a medium pot, add the seeds of the vanilla bean and the pod and the sugar, with 1/2 cup water. Bring to a boil, without stirring, and let cook until the mixture turns a deep amber, start checking for color at 10 minutes. Slowly whisk in the plum puree (it will bubble up!) and keep whisking until everything is combined and any hardened sugar has dissolved. Keep cooking over high heat until mixture thickens a bit, about 5 minutes more. Transfer to a bowl and set aside to cool completely.

4. Make the cake: Heat oven to 350 degrees and line 3, 6-inch cake pans with parchment and grease the pans (or if you don’t have three pans, prepare 2 and bake in batches). In a bowl, sift the cake flour and set aside.

5. To the bowl of a stand mixer, add butter, coconut oil, sugar, baking powder, baking soda, and salt and mix until with the paddle attachment on medium speed until fluffy, about 5 minutes. Add the egg whites and beat to fully combine, then add the vanilla.

6. With mixer on low speed, add the 1/3 of the flour mixture and 1/3 of the buttermilk in alternate batches, starting with the flour and ending with the buttermilk. Divide batter between baking pans and bake 13-15 minutes, until golden on top and toothpick inserted in the middle comes out clean. Remove from pans and let cool completely on a wire rack.

7. While cake layers are cooling, finish the buttercream: transfer the marshmallow base to the bowl of a stand mixer and begin to whip on medium with the whisk attachment. Slowly add the butter, 1 tablespoon at a time, waiting for each to incorporate before adding more. The mixture will loosen up as you go but will look awful at first, keep going! Once all the butter is incorporated, whip for another minute, scraping the bottom as needed to make sure you get all the butter combined with all the marshmallow. Add in the cooled plum caramel and whisk to fully combine.

8. At this point, your buttercream should hopefully be thick, yet light and creamy. However, there’s a good chance it seems a little soupy, if your kitchen is very warm. Just refrigerate the bowl for 15 minute increments, whipping in between, until the buttercream is the right consistency.

9. Assembly! Level your cooled cake layers, and frost the bottom layer with the buttercream. Using an offset spatula, create a shallow well in the center of the frosting and fill with more of the plum caramel. This creates a dam so the caramel doesn’t leak out the sides of the cake. Top with a second cake layer and repeat. Top with the third cake layer, and frost and decorate as desired!

Notes:

• I really recommend using a digital thermometer that you can clip to the side of the pot or bowl for this recipe. The temperature and timing is crucial so you don’t want to be guessing with a regular candy thermometer.