Step 1 – Make the Lemon Cream Filling:
In a saucepan, whisk together egg yolks, sugar, and cornstarch until smooth. Slowly pour in lemon juice while whisking.
Cook over medium heat, stirring constantly, until thickened. Remove from heat, stir in butter, and let cool. Once cooled, fold in whipped cream or mascarpone. Chill until ready to use.
Step 2 – Prepare the Cake Batter:
In a large bowl, beat eggs and sugar until pale and fluffy. Add melted butter (or oil), milk, vanilla, and lemon zest.
In another bowl, whisk flour and baking powder, then fold into the wet mixture. Mix gently to keep it airy.
Step 3 – Bake the Cake:
Preheat oven to 350°F (175°C). Divide batter between two greased 8-inch round pans.
Bake 25–30 minutes, or until a toothpick inserted in the center comes out clean. Let cool completely.
Step 4 – Assemble the Cake:
Place one cake layer on a plate and spread with chilled lemon cream. Top with the second layer and press lightly.
Dust with powdered sugar and garnish with lemon zest or whipped cream if desired.
Step 5 – Chill & Serve:
Refrigerate for at least 1 hour before slicing. Serve slightly chilled for the best flavor and texture.