Strawberry Lemonade Cupcakes

Directions

1. Make the purée: In a small bowl, rub the granulated sugar and lemon zest together. In a medium pot, toss the strawberries and lemon juice to combine. Add the sugar and salt, tossing everything to combine. Cook over medium heat, stirring frequently, until the mixture becomes saucy and the strawberries start to break down, 8 to 10 minutes.
2. Use an immersion blender to purée the mixture in the pot (you can also coarsely mash with a large fork or potato masher). Continue to cook the mixture over medium-low heat, stirring often, until it reduces to ⅔ cup (270 grams), 10 to 15 minutes more. Cool completely before using. This can be done up to 2 days ahead and refrigerated.)
3. Make the cake: Heat the oven to 350°F/175°C. Line two 12-cup muffin tins with cupcake liners.
4. In the bowl of an electric mixer fitted with the paddle attachment, mix the flour, sugar, baking powder, baking soda, and salt to combine. Drop ½-tablespoon-size portions of butter into the bowl, and mix on low speed until the butter is distributed and the mixture looks a bit crumbly.
5. In a large liquid measuring cup, whisk the egg whites, milk, strawberry purée, vanilla, and lemon zest to combine. Add this mixture in two equal additions, mixing on medium speed until the batter is smooth and combined, and scraping well after each addition. If desired, tint the batter deeper pink with food coloring.
6. Scoop the batter into the prepared pan using an ice cream scoop, filling each cavity three-quarters full.
7. Bake the cupcakes until a toothpick inserted into the center comes out clean, or with just a few moist crumbs, 17 to 20 minutes. Cool completely.
8. Make the lemon curd buttercream: Place the egg whites and cream of tartar in the bowl of an electric mixer fitted with the whisk attachment. In a medium saucepan, combine the sugar and water and bring to a boil over medium heat. Stir until the mixture begins to bubble, but as soon as it begins to boil, stop stirring. If necessary, dip a brush in cool water to brush away granules of sugar that appear on the side of the pot.
9. Cook the sugar mixture until it reads 235°F/115°C. Begin whipping the egg whites on medium speed, raising to medium-high speed once the mixture looks frothy. When the sugar mixture reaches 240°F, remove the pot from the heat and gradually add the hot sugar syrup to the mixer in a slow, steady stream. Continue whipping until the meringue has reached full volume and the bowl is no longer warm to the touch, 5 to 6 minutes.
10. With the mixer running on medium speed, gradually add the butter a few tablespoons at a time, mixing to fully combine before adding more. This will take several minutes, and the mixture will look light and fluffy. Remove the bowl from the mixer and mix in the lemon curd with a silicone spatula. I use sort of a folding motion to incorporate it, because it helps to deflate the frosting a bit and make it smoother.
11. For easy frosting: Gently fold the strawberry purée into the frosting, drizzling it in about a third at a time, and folding it a few times but not incorporating it fully. Use an ice cream scoop to transfer swirled frosting on top of each cupcake and use a small offset spatula to swirl it. Skip to skep 16.
12. For fancy frosting: Transfer the frosting to a pastry bag and cut a 1-inch/2½-centimeter opening from the tip. Transfer the strawberry jam to a pastry bag and cut a ¼-inch/6-millimeter opening from the tip. Cut a piece of plastic wrap about 15 inches/38 centimeters wide.
13. Starting about 1 inch/2½ centimeters above the lower edge of the plastic wrap, pipe a line of lemon frosting onto the plastic wrap, then a line of strawberry; continue this until you’ve used all of the frosting and purée. Almost all of the plastic wrap should be covered.
14. Starting at the uncovered edge, roll the plastic up into a tight spiral, twisting the ends gently to secure, then trimming one of the ends off. Transfer this frosting packet into a pastry bag fitted with a large star tip (the cut side of the frosting should go toward the tip).
15. Pipe the frosting on top of each cupcake, starting by piping a ring around the outside edge, then working upward in a spiral.
16. Just before serving, top with a lemon slice and a strawberry half.