Ultimate Lemon Layer Cake Recipe

How to Make Ultimate Lemon Layer Cake

1. **Lemon Filling:**
2. In a small bowl, measure 1 tablespoon lemon juice and sprinkle 1 teaspoon unflavored powdered gelatin over top. Let it bloom for 5 minutes.
3. In a medium, non-reactive saucepan, combine remaining ¾ cup lemon juice, 1 cup granulated sugar, and ¼ teaspoon salt. Heat over medium-high heat, stirring until sugar dissolves and mixture is hot (do not boil).
4. In a large non-reactive bowl, whisk together 4 large eggs and 4 large egg yolks.
5. Whisking constantly, slowly pour the hot lemon-sugar mixture into the egg mixture.
6. Return the mixture to the saucepan. Cook over medium-low heat, stirring constantly, until the mixture reaches 170°F (77°C) and is thick enough to coat the back of a spoon (4-6 minutes).
7. Immediately remove from heat and stir in the bloomed gelatin until completely dissolved.
8. Stir in 6 tablespoons (3 ounces) cold unsalted butter, cut into pieces, until fully incorporated.
9. Pour the filling through a fine-mesh sieve into a bowl. Cover the surface with plastic wrap, pressing it directly onto the filling to prevent a skin from forming.
10. Refrigerate until firm enough to spread, at least 4 hours (or up to overnight).
11. **Cake:**
12. Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans. Line the bottoms with parchment paper.
13. In a medium bowl, whisk together ½ cup buttermilk, 2 large egg whites, and 1 teaspoon vanilla extract.
14. In a large bowl, whisk together 2 ½ cups all-purpose flour, 2 cups granulated sugar, 4 teaspoons baking powder, and 1 teaspoon salt.
15. Using a mixer on low speed, add 1 cup (2 sticks) unsalted butter, one tablespoon at a time, beating until the mixture resembles moist crumbs.
16. Add all but 1 cup of the buttermilk mixture to the crumbs and beat on medium speed until pale and fluffy (about 1 ½ minutes).
17. With the mixer running, gradually add the remaining 1 cup of buttermilk mixture and beat for 1 minute more.
18. Divide the batter evenly between the prepared cake pans.
19. Bake for 23-25 minutes, or until a toothpick inserted into the center comes out clean.
20. Let the cakes cool in the pans for 10 minutes. Then, run a small knife around the edges to loosen, invert onto a wire rack, remove parchment paper, and invert again to cool completely.
21. **Lemon Italian Meringue Buttercream:**
22. In a heatproof bowl, combine ¾ cup granulated sugar, ¼ cup water, and 4 large egg whites.
23. Set the bowl over a saucepan of simmering water (make sure the bottom of the bowl doesn't touch the water). Cook, whisking constantly, until the mixture reaches 160°F (71°C).
24. Transfer the mixture to a stand mixer fitted with a whisk attachment. Beat on medium speed until soft peaks form (about 5 minutes).
25. Increase speed to medium-high and continue beating until the mixture has cooled to room temperature and stiff peaks form (another 5-7 minutes).
26. Gradually add 1 cup (2 sticks) unsalted butter, one tablespoon at a time, beating well after each addition until incorporated.
27. Beat in 1 teaspoon vanilla extract and the zest of 1 lemon.
28. **Assembly:**
29. Carefully slice each cake layer in half horizontally.
30. Spread about 1 cup of the lemon filling evenly onto each cake layer, leaving a ½-inch border.
31. Top with another cake layer and repeat the filling process.
32. Frost the entire cake with the lemon Italian meringue buttercream.
33. Refrigerate for at least 30 minutes before serving to allow the flavors to meld.