Mix 20g cocoa powder into 50g hot milk until smooth.

Divide 3 eggs into yolks and whites, placing them in separate bowls.

Add 30g vegetable oil to yolks and whisk until smooth.

Stir in the cocoa mixture into the egg yolks and oil, combining well.

Sift 40g cornstarch into the mixture and stir gently until smooth.

Beat 3 egg whites with a pinch of salt and 1 tsp lemon juice until foamy, then gradually add 60g sugar in 3 batches.

Whisk until stiff peaks form, then fold 1/3 of the meringue into the egg yolk mixture.

Gently fold the remaining meringue into the batter until just combined.

Pour the batter into a 17 cm (7-inch) tube pan, swirling with a skewer to remove air bubbles.

Tap the pan to remove excess air, then bake at 170°C for 40-45 minutes, testing with a toothpick for doneness.

Let the cake cool completely for about 3 hours before unmolding.

Once cool, trim the top of the cake for an even surface before icing.

Whisk 250 ml heavy whipping cream, 50g mascarpone cheese, and 35g powdered sugar until soft peaks form.

Apply a thin layer of icing to the cake to lock in crumbs.

Cover the cake evenly with a thicker layer of mascarpone icing, smoothing the surface.

Microwave 33g chocolate and 33g heavy cream together until smooth, then cool to 28-30°C.

Pour the ganache over the iced cake, letting it drip down the sides.

Let the ganache firm up for 15 minutes.

Slice, serve, and enjoy the rich, light, and delicious cake.