Lemon–White Chocolate Cupcakes with Blackberry Buttercream

These luscious cupcakes team juicy berries with rich white chocolate to make a special summer treat.

MAKES: 18 cupcakes

PREP TIME: 40 minutes

COOKING TIME: about 30 minutes

INGREDIENTS:

CHOCOLATE CHIPS

• ¾ cup white chocolate chips
• 1 Tbsp all-purpose flour

CUPCAKES

• 1 ¾ cups all-purpose flour
• 1 ½ tsp baking powder
• ½ tsp fine sea salt
• ¼ tsp baking soda
• ⅔ cup unsalted butter, softened
• 1 cup granulated sugar
• 2 large eggs
• 1 Tbsp finely grated lemon zest (1 to 2 lemons)
• 1 Tbsp freshly squeezed lemon juice
• 1 tsp vanilla extract
• ½ cup whole milk

BLACKBERRY BUTTERCREAM

• 1 ½ cups fresh or frozen blackberries
• 2 Tbsp freshly squeezed lemon juice
• 1 Tbsp water
• 1 ½ cups granulated sugar
• 4 large egg whites
• ½ tsp fine sea salt
• 1 ¼ cups unsalted butter, cut into 1-inch pieces and softened
• Additional fresh blackberries and finely grated lemon zest for garnish (optional)

INSTRUCTIONS:

1. Preheat the oven to 350°F. Line two muffins pans with 18 large paper liners, then set aside. Pour water into any empty wells to prevent burning.
2. For the chocolate chips, toss them with the flour in a small bowl. Set aside.
3. For the cupcakes, whisk together the flour, baking powder, salt and baking soda in a medium bowl. Set aside.
4. In a large bowl and using an electric mixer, beat the butter on medium-low speed until creamy. Gradually beat in the sugar, increasing the speed to medium. Beat until pale and fluffy.
5. Turn down the speed to low and beat in the eggs one at a time. Beat in the lemon zest and juice and vanilla extract.
6. Add the flour mixture to the butter mixture alternately with the milk, making three additions of flour and two of milk, and beginning and ending with the flour. Stir until well combined. Fold in the chocolate chips.
7. Fill the paper liners about two-thirds full with batter. Bake until the cupcakes spring back when lightly touched and a wooden skewer inserted in the centre of a cupcake comes out clean, about 20 minutes.
8. Let the cupcakes cool in the pans for 10 minutes, then remove to a wire rack and let cool completely. (The undecorated cupcakes can be refrigerated in an airtight container for up to 4 days.)
9. For the buttercream, stir together the blackberries, lemon juice and water in a small saucepan. Mash the berries well with a fork. Bring to a simmer over low heat, then cook, stirring occasionally, until the mixture has reduced to about ½ cup.
10. Strain the blackberry mixture through a fine-mesh sieve, pressing on the solids to extract as much blackberry purée as possible. Cool and discard the seeds.
11. In a large heatproof bowl, stir together the sugar, egg whites and salt. Set the bowl over a saucepan of simmering water. Whisk constantly until the mixture registers 140°F on an instant-read thermometer, 6 to 8 minutes.
12. Remove the bowl from the heat and, using an electric mixer, beat the mixture on medium-high until it has cooled, about 10 minutes. Turn down the mixer speed to low and beat in the butter, one piece at a time, beating to incorporate after each addition. Beat in the blackberry purée until well combined.
13. Using an offset spatula or a piping bag, swirl the buttercream on top of the cupcakes. Garnish with blackberries and lemon zest.

NOTE

• The frosted cupcakes—without the garnish—can be refrigerated in an airtight container for up to 3 days. Bring them to room temperature before serving.