Lemon Cake

1. Preheat the oven to 165°C / 325°F and line three 15 cm / 6-inch cake pans with parchment paper.
2. In a bowl, sift together the flour, cornstarch, baking powder, baking soda, and salt.
3. In a large bowl, beat the softened butter with powdered sugar and lemon zest for 2–3 minutes until creamy.
4. Add the eggs and vanilla and beat again for 3–5 minutes until smooth.
5. Alternate adding the dry ingredients and the buttermilk mixed with lemon juice, folding gently with a spatula until smooth.
6. Divide the batter evenly between the pans and bake for about 30 minutes, until golden and set in the center.
7. Let cool briefly, then unmold and cool completely on a wire rack.

Strawberry Filling

1. Combine the strawberries, sugar, and lemon juice in a saucepan.
2. Cook over medium heat for 12–15 minutes, stirring occasionally, until softened but slightly chunky.
3. Cool completely, then transfer to a jar and refrigerate.
4. Before assembling, blend 100 g of the compote into a smooth purée for the buttercream.

Swiss Strawberry Buttercream

1. Heat the egg whites and sugar over a double boiler, whisking constantly, until the sugar dissolves and the mixture reaches 160°F / 71°C.
2. Whip in a stand mixer until stiff, glossy, and completely cool.
3. Add the butter gradually, then beat until smooth and thick.
4. Mix in the strawberry purée and vanilla just until combined.
5. Switch to the paddle attachment and mix on low for 1–2 minutes to smooth the buttercream.

Lemon Mascarpone Frosting

1. Combine the cold mascarpone, heavy cream, lemon curd, powdered sugar, and vanilla in a bowl.
2. Whip on low to medium speed for about 2 minutes, until smooth and firm.

Cake Assembly

1. Level the cake layers if needed.
2. Place the first layer on a cake board and pipe a buttercream border, then fill with strawberry compote and lemon mascarpone cream.
3. Repeat with the remaining layers.
4. Apply a thin crumb coat of strawberry buttercream, then frost with a thicker layer and smooth using a spatula or icing scraper.
5. Chill the cake for at least 2 hours (or 30 minutes in the freezer).

Lemon Drip

1. Melt the white chocolate and heavy cream over a double boiler until smooth.
2. Stir in the lemon curd and yellow food coloring.
3. Let cool to 30°C / 86°F, then drip over the chilled cake.
4. Decorate with piped strawberry buttercream and lemon slices.
5. Remove the cake from the fridge 20–30 minutes before serving.