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London fog cupcakes

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Swiss buttercream differs from American in that it’s made from butter whipped into meringue, instead of butter whipped solely into powdered sugar. I was utterly convinced I was going to screw it up on the first try, but it turned out to be more forgiving than I could have imagined, and whips up into, like Tessa says, a buttercream that is infinitely easy to spread and frost with. The extra egg whites make the frosting less sweet than a traditional buttercream, and at the same time lend a springy sturdiness that is a dream to work with. Not to mention it tastes incredible. I hope you enjoy it as much as I do!

Recipe reprinted with permission from Layered by Tessa Huff, and slightly adapted to be made without a stand mixer (and for cupcakes).

Ingredients

Scale
  • for the yellow butter cake:
  • 3 1/4 cups (425 g) cake flour
  • 1 tbsp baking powder
  • 3/4 tsp salt
  • 1 cup (2 sticks or 225 g) unsalted butter, room temperature
  • 2 cups (400 g) granulated sugar
  • 2 tsp vanilla bean paste (or vanilla extract, in a pinch)
  • 6 large egg yolks (save the egg whites for the buttercream, below)
  • 1 1/2 cups whole milk (see Notes for Earl Grey-infused milk)
  • for the Earl Grey Swiss buttercream:
  • 2 cups unsalted butter, room temperature
  • 1/2 cup loose Earl Grey tea (or the tea from about 5–6 Earl Grey teabags, cut open)
  • 1/2 cup plus 2 tablespoons large egg whites
  • 1 1/4 cup granulated sugar
  • 1 1/2 tsp vanilla bean paste (or vanilla extract, in a pinch)
  • to serve:
  • about 1/4 cup salted caramel sauce (see here for my favorite recipe)
  • 1 tsp lavender (optional)

Instructions

  1. For the cake: Preheat the oven to 350 F. Grease and flour two 8-inch (20-cm) cake pans, or line your cupcake pans.
  2. Sift together the flour, baking powder, and salt and set aside.
  3. In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on medium speed until smooth. (If you don’t have one, like me, simply use a hand-held electric beater.) Add the sugar and mix on medium-high until the butter is light and fluffy, 3-5 minutes. Stop the mixer and scrape down the bowl.
  4. Turn the mixer to medium-low and add egg yolks, one at a time followed by vanilla bean paste. Stop the mixer and scrape down the bowl.
  5. Turn the mixer to low (or switch to using a spatula) and add the flour mixture in three batches, alternating with the milk in two batches, beginning and ending with the flour mixture. Mix on medium speed for no longer than 30 seconds after the last streaks of the dry ingredients are combined.
  6. If making cupcakes: Fill liners slightly more than half and no more than 2/3 full (the cake will rise considerably) and bake for about 18-20 minutes, or until a toothpick inserted into the center of a cupcake comes out clean. I started testing early, since butter-based cakes can dry out with over-baking. ( Note: This will make several batches of cupcakes. Your extra batter can sit at room temperature while batches bake without issue.) Let the cupcakes cool while you make the frosting.
  7. If making a 9-inch cake: Evenly divide the batter between your two 8-inch cake pans and bake for 25 to 28 minutes, or until a toothpick inserted into the center of the cakes comes out clean. Let them cool on a wire rack for 10-15 minutes before removing the cakes from their pans. Once removed, let cool completely while you make the buttercream, or wrap and freeze for easier assembly.
  8. For the buttercream: Place 1 cup (225 grams) of the butter in a saucepan with the loose tea. Heat over medium heat until the butter melts, then reduce the heat to low and simmer for 5 minutes. Remove from the heat and let the tea steep for 5 minutes more. Strain the butter through a fine-meshed sieve set over a bowl and refrigerate it until it reaches the same consistency as softened butter, 20 to 30 minutes. Small bits of tea may remain in the butter.
  9. Place the egg whites and sugar into a very large bowl or the bowl of a stand mixer. Whisk them together by hand to combine. Fill a medium saucepan with a few inches of water and place it over medium-high heat. Place the bowl with the egg white mixture on top of the saucepan to create a double boiler. The bottom of the bowl should not touch the water. Whisking intermittently, heat the egg mixture until it reaches 160°F on a candy thermometer or is hot to the touch. Carefully remove the bowl and, if using, fit the mixer bowl onto the stand mixer.
  10. With the whisk attachment or a handheld electric beater, beat the egg white mixture on high speed for 8 to 10 minutes, until it holds medium-stiff peaks. When done, the outside of the mixer bowl should return to room temperature and no residual heat should be escaping from the meringue out of the top of the bowl. If using, stop the mixer and swap out the whisk attachment for the paddle.
  11. With the mixer on low speed, add the vanilla, tea infused butter, and remaining 1 cup (225 grams) butter, a couple tablespoons at a time. (An electric beater also works fine for this.) Once incorporated, turn the mixer to medium-high and beat until the buttercream is silky smooth, 3 to 5 minutes.
  12. To assemble: For the cupcakes, simply frost as desired, top with a drizzle of caramel sauce (and lavender, if desired) and enjoy! For a layer cake, carefully halve the two layers horizontally to create four even layers of cake. Level the cakes and choose which layer will be the bottom. Place it on a cake plate, turning table, or serving dish. Spread on about 1/2 cup (120 ml) of the buttercream with an offset spatula. Top with the next layer of cake and repeat, ending with the fourth layer. Frost the cake with the remaining buttercream and refrigerate it until set, 15 to 20 minutes.
  13. Pour caramel sauce onto the top of the cake, letting it drip over the edges. Begin by adding 1/2 cup of caramel to the center of the cake and then smooth it out with an offset spatula. Add more caramel as necessary until desired look is achieved. (You can see Tessa’s blog, or her book (of course) for a bunch of other beautiful frosting ideas!)

Notes

To add a touch of tea to the cake, as well, warm the milk in a saucepan or in the microwave until just steaming but not simmering, and add 1/4 cup loose leaf Earl Grey tea (or 3-4 tea bags). Let steep in the refrigerator until completely cool and milk is a deep caramel, then use as directed. If using regular milk, note that your cake will be quite a bit lighter when fully baked.

I have not tried these as miniature cupcakes, but I would suggest baking for 12-15 minutes, and start testing early. I found my cupcakes to be best when the cake indented slightly when touched and did not immediately bounce back, but felt firm and did not deflate.

Finally, to make miniature layer cakes, you can bake these in 4-oz porcelain ramekins (I use these) filled about halfway, for about 22-24 minutes.

Find it online: https://tworedbowls.com/2016/04/20/london-fog-cupcakes/