Combine milk, butter and lemon zest in a small saucepan over medium heat and bring to a simmer. Remove from heat and let stand for 10 minutes to infuse.

Sift flour, corn starch and baking powder into a medium bowl. Add salt and whisk to blend evenly.

Combine whole eggs, yolks and sugar in the bowl of a stand mixer fitted with the whisk attachment and beat on medium-high speed for 2 minutes. Increase to high speed and beat for 4 minutes until pale, thick and tripled in volume. Mix in vanilla and lemon juice. With the mixer on medium speed, slowly pour in the warm milk mixture and mix just until incorporated. With mixer on low, gradually add flour mixture until combined and batter is smooth.

Pour batter into prepared pan and bake for 30-35 minutes until evenly golden and a toothpick inserted in the center comes out clean. Transfer pan to a wire rack to cool for 20 minutes. Run a knife around the edges of the pan, invert to release the cake and allow to cool completely.

For the topping, whip cream to soft peaks using an electric mixer and spread over cooled cake. Dollop teaspoons of chilled lemon curd over the cream and swirl it through. Serve with extra curd on the side.