Sponge Cake With Prune Plum & Strawberry SMBC
Makes: 1, 3-layer, approximately 4” cake
Let me be honest - this isn’t an authentic version of Swiss Meringue Butter Cream (SMBC) at ALL.
I did start with good intentions; headed over to Sally’s Baking Addiction, found the right recipe, watched the troubleshooting tips prior to beginning my shenanigans. In short, I did my due diligence. But somewhere between the midnight baking frenzy and never-ending beating of cooked egg white that just wouldn’t f*cking stiffen, there came a stark realization that if this didn’t end soon, I would get under 6 hours of sleep prior to a taxing hike I had committed to, for the following day.
So, I did what I knew best; threw in some corn starch and confectioner’s sugar, “fixed” my frosting, ate a huge slice of cake, and went to bed, utterly satisfied. In conclusion, this is an SMBC by definition - albeit, a hack job of it, which only makes it so much better ;)
ingredients
GROUP A: CAKE
1 egg
1/2 stick (2 oz) salted butter
1/4 cup fine granulated brown sugar
1/4 cup bread flour (substitute: equal part AP flour)
Pinch of baking powder
1 tsp marmalade
1/4 tsp vanilla extract
GROUP B: FRUIT PURÉE
3 prune plums
3 medium strawberries
1 tsp brown sugar
GROUP C: HACKJOB SMBC
1 egg white
45 g white granulated sugar
72 g salted butter, softened at room temperature
Pinch of salt
1/2 tsp cornstarch
2 tbsp powdered sugar
GROUP D: EVERYTHING ELSE
3 - 4 tbsp lime curd (follow this recipe)
1 tsp fresh lime zest
notes
Feel free to use any cake mold of choice, but I recommend sticking to a small ramekin or cake ring, so that the batter will have sufficient height to rise to, and slicing the cake into half, height-wise, will become far easier. A larger mold may also significantly reduce your baking time, since your surface area for the same amount of batter will increase.
Don’t get lazy creaming the butter and sugar; ensure that no flecks/granules of sugar are visible and the consistency of the final mixture should be like the whipped butter, or even moisturizer, that you can buy at stores.
The cake is small enough that it can be finished in a day; on the off chance that you want to store it for eating later, refrigerate it in an air tight box for up to 2 days. In this case, be sure to let it “warm” up at room temperature for at least 30 minutes before eating.
method
Bake the cake: Preheat the oven to 350 F. Grease and dust your cake mold of choice ( I used an ≈ 4” ramekin). In a deep bowl, cream the butter and sugar together till the mixture is pale and light, as opposed to the dark brown (sugar) & yellow (butter) combination in the beginning. Whisk in the egg and vanilla till the mixture becomes uniform. Add half the flour and the marmalade, and fold the batter gently; it’s okay to have flour streaks. Add the remaining flour and the baking powder, and this time, fold till there is no dry streak remaining. Pour the batter into the prepared mold and bake for 15 - 20 minutes, till the cake has risen and skewer inserted into its center comes out clean. Pop the cake onto a wire rack and let it cool completely at room temperature for 25 - 30 minutes.
Prep the fruit: Pit the prune plums. Cut all the fruit into quarters. Add all Group B ingredients to a small saucepan and cook on medium heat till the mixture is sticky, jammy, and slightly thick. Take it off the heat once it reaches this consistency, let it cool to room temperature, and toss into a blender with 2 tablespoons of water. Blend into a purée and strain to discard the solids. Set aside.
Make the buttercream frosting: Wipe a clean, deep bowl and the whisk attachment on your mixer with white vinegar, to ensure that there is no remnant grease or fat on either. Add the egg white and granulated sugar to the bowl. Heat up a saucepan with water. Place a grid (such as a cooling rack) or a few skewers criss-crossed over the pan, then place the bowl on the grid. Ensure that the bowl does not touch the water directly by any means. Whisk gently but continuously and keep feeling the texture with your fingers - when it stops feeling granular, take it off the heat immediately. Now, whisk the mixture with an electric beater on high speed till it is thick, a little viscous, and bright white. Add the butter, cornstarch, powdered sugar, and fruit purée, and whisk on medium-high speed till the frosting comes together as one smooth mixture.
Assemble the cake: Slice the cake height-wise, to yield 3 discs of cake. Spread or pipe the frosting on the base disc, then layer on the lime curd. Repeat once again. When the top-most cake layer has been placed, frost the entire cake with the remaining SMBC (you might still have some left over), then finish it by sprinkling the fresh lime zest on the top.
