Preheat the oven: Set your oven to 350°F (175°C). Prepare a mini muffin or cupcake pan by lightly greasing it or lining with paper cups.

Separate eggs: Separate the egg whites and yolks into two clean bowls.

Beat egg whites: Using an electric mixer, beat the egg whites until soft peaks form. Gradually add half the granulated sugar (30 g) and continue beating until stiff peaks form.

Mix yolks and wet ingredients: In the other bowl, whisk together the egg yolks, vegetable oil, milk, lemon juice, vanilla extract, and the remaining sugar until smooth.

Sift flour: Sift the cake flour into the yolk mixture, folding gently until just combined.

Fold egg whites: Carefully fold the beaten egg whites into the yolk mixture in batches, being careful not to deflate the mixture. Use a spatula to fold until just incorporated and smooth.

Fill molds: Spoon the batter into the prepared mini muffin tins, filling about 3/4 full.

Bake: Bake for 12-15 minutes or until the tops are golden and a toothpick inserted into the center comes out clean.

Cool: Allow cakes to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.