Preheat oven to 165°C (325°F) and prepare three 15 cm (6 inch) cake pans with parchment paper. Sift together flour, cornstarch, baking powder, baking soda, and salt. In another bowl, beat softened butter, powdered sugar, and lemon zest with an electric mixer on medium speed until creamy. Add eggs and vanilla extract, mixing until smooth. Gradually incorporate the buttermilk and lemon juice into the dry mixture to form a homogeneous batter.

Distribute the batter evenly among the cake pans. Bake for 30 minutes or until golden and a toothpick inserted in the center comes out clean. Cool briefly in the pans, then transfer to a wire rack to cool completely.

Cook homemade strawberry compote and allow it to cool completely.

Make the Strawberry Swiss Buttercream per recipe instructions.

Prepare the Lemon Mascarpone Chantilly according to the recipe.

Level cake layers if needed. Place the first layer on a turntable and add a border of strawberry buttercream. Fill with strawberry compote and lemon mascarpone chantilly. Repeat with the second and third layers. Apply a crumb coating with buttercream and chill in the fridge for at least 2 hours or 30 minutes in the freezer.

Melt white chocolate with heavy cream over a double boiler. Stir in lemon curd and yellow food coloring, and cool glaze to 30°C (86°F). Pour over the chilled cake, letting it drip down the sides. Decorate with remaining buttercream and lemon slices. Allow the cake to sit at room temperature for 20-30 minutes before serving.