Preheat the oven to 350°F (175°C) and prepare a 9-inch round baking pan by greasing and lining with parchment paper.

Separate egg whites from yolks and let them come to room temperature.

Whisk egg yolks and granulated sugar for 2–3 minutes until pale and creamy.

Stir in melted butter and vanilla, then fold in flour. Add lemon juice and zest, and mix until smooth.

Gradually add milk to the batter until fully combined and smooth.

Beat egg whites until stiff peaks form, then gently fold into the batter in three additions.

Pour the batter into the prepared pan and bake for 40-60 minutes, until firm but slightly jiggly in the center.

Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Dust with powdered sugar before serving.