Strawberry Lime Layer Cake

Ingredients

• For the white cake:
• 3 cups (about 360 g) cake flour
• 2 teaspoons baking powder
• 1 teaspoon salt
• 1 1/2 cups (340 g) unsalted butter, at room temperature
• 2 1/4 cups (450 g) granulated sugar, divided
• 1 teaspoon vanilla extract
• 1 cup (240 ml) milk, at room temperature
• 8 large egg whites, at room temperature (save the yolks for the curd)
• For the coconut lime curd:
• 1 can (13.5 to 15 oz) full-fat coconut milk, well stirred
• 1 cup (200 g) granulated sugar
• 1/3 cup (40 g) cornstarch
• 1/3 cup (75 g) unsalted butter
• 1/2 cup (120 ml) fresh lime juice (about 4 limes)
• 6 large egg yolks, lightly beaten
• Green food coloring (optional)
• For the whipped strawberry frosting:
• 2 cups (454 g) unsalted butter, softened
• 4 cups (about 480 g) powdered sugar, sifted
• 1/4 cup (60 ml) strawberry purée (from fresh or thawed frozen berries)
• 2 teaspoons vanilla extract

Steps

1. Make the curd first so it has time to chill: in a medium saucepan over medium-high heat, warm 1 cup of the coconut milk with the 1 cup sugar, stirring until the sugar dissolves.
2. Whisk the cornstarch into the remaining coconut milk until smooth, then pour it into the saucepan, stirring. Turn the heat down to medium and whisk in the butter until melted.
3. Whisk in the lime juice and egg yolks. Cook, stirring often, until the curd is thick enough to coat the back of a spoon, about 5 to 8 minutes; keep the heat moderate so the yolks do not scramble. Stir in a drop of green coloring if you like.
4. Let the curd cool for a few minutes, transfer it to a heatproof bowl and press plastic wrap directly onto the surface. Cool to room temperature, then refrigerate for at least 2 hours.
5. For the cake, heat the oven to 350°F. Line two 9-inch round cake pans with parchment rounds and grease them.
6. Sift the cake flour, baking powder and salt together into a bowl.
7. In a large bowl, beat the butter with 2 cups (400 g) of the sugar for 3 to 4 minutes, until pale and fluffy. Beat in the vanilla.
8. With the mixer on low, add the flour mixture in three parts, alternating with the milk in two parts, beginning and ending with flour. Mix only until no dry streaks remain.
9. In a clean bowl with clean beaters, whip the egg whites on low until foamy. Add the remaining 1/4 cup (50 g) sugar, raise the speed to high and whip just until stiff, glossy peaks form.
10. Stir about one third of the whites into the batter to lighten it, then gently fold in the rest until no white streaks remain.
11. Divide the batter between the pans and smooth the tops. Bake for 30 to 35 minutes, until a toothpick inserted in the center comes out clean.
12. Cool the cakes in the pans for 20 minutes, then turn them out, peel off the parchment and cool completely on a wire rack.
13. For the frosting, beat the butter in a stand mixer for about 6 minutes, until very pale and creamy. Add the powdered sugar, strawberry purée and vanilla and beat for another 6 minutes, until light and fluffy.
14. To assemble, level the tops of the cooled cakes with a serrated knife, then slice each cake horizontally into two even layers.
15. Set one layer on a serving plate. Beat the chilled curd briefly to loosen it and spread a thin layer over the cake. Repeat with two more layers of cake and curd, then top with the last cake layer. You will have some curd left over.
16. Spread a thin crumb coat of frosting over the whole cake to seal in the crumbs and keep the curd from showing. Chill for 10 minutes.
17. Finish frosting the cake as you like, then refrigerate until serving. Let it sit out for about 20 minutes before slicing.