20 May 2014

Elderflower Cupcakes

The Art.
    I love baking in the springtime, because I get to try out all my ideas for making light, flowery desserts. I recently discovered Fleur Elderflower Liqueur, and I immediately knew I had to put it in some cupcakes. It has a beautiful floral flavor that is slightly sweet, with a hint of citrus. Further inspiration came to me when I saw this pattern for doily cupcake wrappers. So, I topped light-as-air angelfood cupcakes with elderflower meringue icing and candied violets, then adorned them with the wrappers. We enjoyed these on Easter with champagne and they were heavenly!

The Science.
    The cake and the icing in these cupcakes are impossibly airy because of one thing: beaten egg whites. Angelfood cake has no leavening agents, and depends solely upon the air bubbles trapped inside the beaten egg whites to provide volume. The meringue icing produces a large volume of fluffy white peaks using only a single egg white. So, what is so special about beating egg whites that makes our dessert so fluffy? The answer is, the hydrophobic domains in the egg albumin protein. When egg whites are beaten at high speed, the "water-fearing" parts of the protein are exposed, and begin to aggregate together because they don't like touching the water. This creates a film that traps the air bubbles as they're beaten in. Angelfood and meringue are fat-free, because any fat in the mixture would bind the hydrophobic domains of the egg albumin and prevent the protein aggregation. This is why it is very important to make sure that your bowls and beater blades are immaculately clean. Furthermore, the meringue is heated over a double boiler to help "fix" the proteins in their aggregated conformation, and cream of tartar also helps stabilize the peaks.

The Recipe.

Angelfood cupcakes:
1/3 cup cake flour
1/2 cup sugar
5 large egg whites
1/4 teaspoon salt
1/2 teaspoon cream of tartar

    Preheat oven to 300oF. Line a cupcake tin with paper liners. Sift flour twice, then sift together with 1/4 cup sugar. Sifting several times aerates the flour so the cake will be lighter. In a large bowl, beat egg whites on medium-high speed until frothy. Add salt and cream of tartar and beat until peaks barely form. Gradually beat in remaining 1/4 cup sugar, mixing until soft peaks form. Gently fold in a third of the flour/sugar at a time, stirring until incorporated after each addition. Fill cupcake tin to the top with batter. Lift and drop the pans onto the counter a couple times to release air bubbles. Bake on center rack until tops are springy and toothpick inserted in center comes out clean, about 25  minutes. Cool 10 minutes, then transfer to cooling rack until room temperature. Can be stored in an air-tight container in the freezer for two weeks. Yields 12 cupcakes.
 
Elderflower Icing:
1/2 cup sugar
3 tablespoons water
1 large egg white
1/8 teaspoon cream of tartar
Pinch of salt
2 tablespoons Fleur liqueur

    Bring one inch of water to a simmer in a medium saucepan.  Combine all ingredients in a large metal bowl, then set over saucepan to create a makeshift double-boiler.  Blend on high speed until soft peaks form, about 5 minutes. Wear an oven mitt on your hand that is stabilizing the bowl, to protect it from the steam. Remove from heat, and beat until icing is cool and billowy with stiff peaks, about 2 minutes.

Assembly:
Place a #1A tip in a piping bag and fill with icing. Pipe a swirl onto each cupcake, starting from the outside and working toward the center. Top with candied violet petals, or your favorite decorations. Place cupcakes in doily wrappers and enjoy!