The Tomboy Cake

Ingredients:
1 cup (2 sticks) unsalted butter, room temperature, plus more
2 1/2 cups all-purpose flour plus more
1 cup slivered almonds
4 teaspoons baking powder
1 1/2 teaspoons kosher salt
1 cup whole milk
2 teaspoons vanilla extract
2 1/2 cups sugar, divided
4 large egg yolks
6 large egg whites
1/4 teaspoon unflavored gelatin
1/3 cup fresh lemon juice
1/3 cup sugar
2 large eggs
6 tablespoons (3/4 stick) unsalted butter, cut into 1/2" pieces
1 cup chilled heavy cream
2 tablespoons powdered sugar
3/4 cup plus 2 tablespoons sugar
1/8 teaspoon kosher salt
3 large egg whites
1/4 teaspoon cream of tartar
1/2 teaspoon vanilla extract
2/3 cup strawberry jam
Three 8"-diameter cake pans with 2" sides; a candy thermometer; a pastry bag; a large star piping tip

Instructions:
Arrange racks in upper and lower thirds of oven; preheat to 350°F. Butter and flour cake pans. Line bottom of pans with parchment–paper rounds; butter paper. Pulse 2 1/2 cups flour and almonds in a food processor until almonds are finely ground. Transfer to a medium bowl and whisk in baking powder and salt; set aside.
Combine milk and vanilla in a measuring cup; set aside. Using an electric mixer, beat 2 cups sugar and 1 cup butter in a large bowl until light and fluffy, 3–4 minutes. Add egg yolks and continue to beat, occasionally scraping down sides and bottom of bowl, until pale yellow and fluffy, 4–5 minutes. Add dry ingredients in 3 additions, alternating with milk mixture in 2 additions, beginning and ending with dry ingredients. (Do not overmix or cake will dome and be dense.)
Using an electric mixer with clean, dry beaters, whip egg whites in a medium bowl until light and frothy. With mixer running, gradually add remaining 1/2 cup sugar. Beat meringue until medium peaks form, 3–4 minutes.
Fold 1/4 of meringue into batter just until incorporated (this will lighten batter, making it easier to fold in remaining meringue). Gently fold in remaining meringue until fully incorporated. Divide batter evenly among prepared pans. Smooth tops.
Bake cakes, rotating from left to right and top to bottom halfway through, until golden brown and the sides of cakes begin to pull away from pans, 40–45 minutes. Transfer to wire racks. Let cakes cool in pans for 10 minutes. Invert cakes onto racks; peel off parchment and let cool completely.
If needed, use a long serrated knife to trim dome from each cake (about 1/8") to create a flat surface. DO AHEAD: Cakes can be made 1 day ahead. Wrap tightly in plastic wrap and store at room temperature.
Place 2 teaspoons cold water in a small bowl; sprinkle gelatin over. Let stand until gelatin softens, about 10 minutes.
Whisk lemon juice, sugar, and eggs in a medium metal bowl; place over a large saucepan of simmering water and cook, whisking constantly, until mixture thickens, 5–6 minutes. (Do not allow bottom of bowl to touch the water or mixture will cook too fast and eggs may scramble.)
Remove bowl from heat and transfer mixture to a blender. With blender running, add butter 1 piece at a time until butter is completely incorporated. Add softened gelatin and blend 30 seconds longer.
Transfer lemon curd to a medium bowl and place a piece of plastic wrap directly on the surface of the curd. Chill until cold and set, 3–4 hours or overnight.
Using an electric mixer, beat chilled cream in another medium bowl until soft peaks form (warm cream will not whip up). Add powdered sugar. Continue to beat until medium peaks form, 2–3 minutes. Whisk curd to loosen; gently fold in whipped cream; set aside. DO AHEAD: Lemon cream can be made 1 day ahead. Cover and chill.
Bring 3/4 cup sugar, salt, and 1/4 cup water to a boil in a small saucepan, stirring to dissolve sugar. Cook without stirring until candy thermometer registers 240°F, 4–5 minutes.
Meanwhile, using an electric mixer, beat egg whites in a medium bowl until light and frothy (be sure to keep a close eye on the sugar syrup). Beat in remaining 2 tablespoons sugar and cream of tartar.
With mixer running, gradually add hot syrup in a thin stream, allowing syrup to drizzle down side of bowl into egg whites. Beat until egg whites are tripled in volume and meringue is very fluffy, cool, and opaque white, about 12 minutes with a stand mixer and up to 20 minutes with a hand mixer. (Frosting made with a hand mixer may not be as firm as that made with a stand mixer.) Add vanilla and mix 1 minute longer. Use meringue immediately.
Fill a pastry bag fitted with large star tip halfway with prepared meringue.
Place 1 cake layer on a cake stand or platter. Spread 1/3 cup strawberry jam over, leaving a 1" border around edge. Spread 1/3 cup lemon cream over jam, keeping 1" border. Pipe a ring of meringue frosting over 1" border around edge. Place second cake layer atop meringue, pressing slightly to adhere. Repeat process with second cake layer, jam, lemon cream, and meringue. (Cover and chill remaining lemon cream for another use.) Place remaining layer on top. Using offset spatula, generously spread remaining meringue frosting on top layer of cake. Chill up to 4 hours.