Lemon Surprise Cupcakes

I love the happy taste combination of tangy lemon and sweet berries. Throw in a little cake and you have a party. With Mother's Day on the horizon what better way to celebrate than with luscious lemon cupcakes crowned with ripe berries to honor our wonderful mothers who bring sunshine and joy to our lives.

Lemon is the predominate flavor throughout starting with lemon cupcakes with a 'surprise' center of lemon curd. The cupcakes are frosted with a simple lemon mousse frosting made by folding lemon curd into stiffly beaten whipped cream.

The cupcakes are delicious on their own, but adding berries elevated a humble cupcake to a pretty little dessert reminiscent of berry shortcake. The recipe may seem long, but each part is fairly quick to make. The lemon curd and the cupcakes can be made a day ahead. Refrigerate until ready to use. I used strawberries and raspberries, but blueberries would also work well in combination or on their own.

I am on a flavored-sugar kick lately. Scenting sugar with citrus zest or vanilla bean seeds gives such a flavor boost. Plus the smell is intoxicating. Recently, I used vanilla-scented sugar in the Easter Egg Vanilla-Scented Sugar Cookies recipe, in this recipe I flavor the sugar with lemon zest both for the cupcakes and the lemon curd. Rubbing the lemon zest with the sugar releases the oils in the zest greatly enhancing the lemon flavor.

Beaten egg whites are folded into the lemon batter to lighten it. Often when you try to fold plain egg whites into another batter it is difficult because the whites break into chunks or 'boulders' as I learned at Tante Marie's Cooking School. I don't remember the science behind it but if you add some granulated sugar when beating the egg whites they stay pliable enough to be easily folded into another batter. Thus eliminating streaks of unmixed egg whites.

If you chill the cupcakes first it is easier to remove the cake from the center with a melon ball scoop or small spoon.

When my husband gave me a free standing Kitchen Aid mixer as an anniversary gift a friend suggested I purchase another mixing bowl. It was rather expensive and at the time I thought a bit extravagant. But it turned out to be great advice as I often use more than one mixing bowl with baking. If you bake a lot you might consider doing the same.

If you don't have two mixing bowls for your standing mixer put the beaten egg whites in another bowl then wash, dry, and reuse the first bowl to make the cupcake batter.

Lemon Surprise Cupcakes
makes 24 cupcakes

Make the lemon curd first, so it can chill while making the cupcakes. Refrigerate the lemon curd and the cupcakes in separate tightly sealed containers for up to a day ahead. The lemon mousse frosting takes just a few minutes to make. Only assemble the cupcakes a few hours before serving so the fruit stays nice. Refrigerate until ready to serve.

Lemon Curd
makes 2 cups

The lemon zest is strained out of the curd before it is cooled, but it adds a deep lemon flavor.

2 whole eggs, plus 8 egg yolks
zest from the lemons
2/3 cup (158 ml) fresh lemon juice (about 6 lemons)
1 cup (200 g) granulated sugar
2 tablespoons unsalted butter, cut into small pieces

Put a fine-mesh strainer over a glass bowl large enough to hold 2 cups of lemon curd. Put the sugar and zest in a heatproof bowl. Rub the zest into the sugar using your fingertips until well combined and fragrant. Add the eggs and egg yolks to the sugar/zest mixture and whisk to combine. Stir in the lemon juice. Cook mixture over a pan of simmering water whisking constantly until mixture is thick enough to coat the back of a spoon. Remove from the heat and whisk in the butter a little at a time until completely smooth. Strain the mixture into a glass bowl. (Straining the mixture removes the lemon zest.) Press plastic wrap onto the surface to prevent a skin from forming. Refrigerate until well chilled at least two hours. Can be made a day ahead.

Cupcakes
makes 24 cupcakes

1 1/2 cups (12 ounces/ 339 g) unsalted butter, at room temperature
2 3/4 cups (390 g) all-purpose flour
1/2 teaspoon baking soda
2 teaspoons baking powder
1/2 teaspoon salt
3 large eggs, separated, at room temperature
1 1/4 cups (250 g) granulated sugar
1 teaspoon lemon zest
2 tablespoons (15 ml) fresh lemon juice
1 teaspoon vanilla extract
3/4 cup (6 ounces/170 g) whole-milk yogurt
fresh berries (strawberries, raspberries, blueberries or a combination)

Preheat the oven to 350℉ (175℃). Line 24 muffin tins with paper liners. In a bowl whisk together the flour, baking soda, baking powder, and salt. In another bowl combine 3/4 cup (150 g) sugar and lemon zest. Using the tips of your fingers work the sugar and zest until mixed together and fragrant.

Using a standing mixer with a whisk attachment beat egg whites until soft peaks form. Gradually add 1/2 cup (100 g) sugar continue beating until stiff peaks form that are glossy, but not dry. (Transfer mixture to a bowl if you only have one mixing bowl.)

Put butter in the mixing bowl switch to a paddle attachment and cream the butter until light about 2 minutes. Add the sugar/lemon zest mixture and beat until pale and fluffy. Add egg yolks, one at a time. Beat until incorporated scraping down the sides of the bowl a few times. Mix in lemon juice and vanilla extract. With the mixer on low speed alternate adding the flour and yogurt in three batches. Mix just until combined. Scrap down the sides of the bowl with each addition. Remove from the mixer, using a large rubber spatula stir one-third of the egg white mixture into the batter to lighten, then gently fold in the remaining egg whites. Don't over-mix.

Fill each paper lined muffin tin three-quarters full. Bake until cupcakes are golden and a tester comes out clean, about 20 minutes. Cool on a wire rack for a few minutes then remove from the tins to cool completely on the rack. Cool cupcakes completely before filling and frosting.

Lemon Mousse Frosting

1 1/4 cups (312 ml) heavy whipping cream
1 cup (240 g) lemon curd

Beat the whipping cream until stiff peaks form. Gently fold the lemon curd into the stiff whipped cream until combined. Use to frost the cupcakes with a knife or a pastry bag fitted with a star tip. If the mixture gets too soft you can beat again for a few minutes. The frosting will not be extremely stiff. It will get firmer once refrigerated.

To assemble cupcakes - use a melon-ball scoop or small spoon to remove a small amount of cake from the center of each cupcake. (Reserve the left-over cupcake balls for another use.) Fill a pastry bag fitted with a large plain round tip with remaining Lemon Curd (about 1 cup/240 g). Fill each cupcake with some Lemon Curd. (Or fill a Ziploc bag with Lemon Curd and cut one corner to use as a pastry bag.)

Frost each cupcake with Lemon Mousse Frosting. Use a knife to frost or fill a pastry bag fitted with a star tip and frost in concentric circles. Decorate the tops with berries. The lemon curd and cupcakes can be made up to a day ahead. Fill, frost, and decorate up to two hours before serving. Refrigerate until ready to serve in a tightly covered container. Store cupcakes in the refrigerator.