Heat the oven to 350°F (175°C). Grease two 8-inch cake pans, line the bottoms using parchment paper, then lightly dust the sides using flour.

Whisk together all-purpose flour, cornstarch, baking powder, baking soda, and salt inside a medium bowl until evenly blended.

Beat softened butter, vegetable oil, and granulated sugar until pale and fluffy. Add eggs individually, mixing completely after each addition. Stir in vanilla extract, grated zest, and fresh lemon juice.

Fold the dry mixture into the wet mixture in three additions, alternating between portions of milk. Continue only until a smooth batter forms without overmixing.

Divide the batter evenly between the prepared pans. Bake for 30–35 minutes until the centers spring back after a gentle touch. Cool inside the pans for 10 minutes before transferring onto a wire rack.

Slice each cooled layer if desired for extra filling. Spread an even layer of prepared lemon curd across the cake before stacking the remaining layer carefully on top.

Place egg whites, sugar, and salt over gently simmering water. Whisk continuously until the sugar dissolves completely. Remove from the heat and beat until stiff, glossy peaks develop. Blend in vanilla extract during the final minute.

Cover the assembled cake generously using the freshly whipped meringue. Create decorative swirls across the surface using an offset spatula.

Toast the outside lightly using a kitchen torch until golden. Refrigerate briefly before slicing so the layers settle neatly. Serve chilled or slightly cool for the best texture.