Mix egg yolks and sugar in a bowl until pale and creamy.

Add milk, vegetable oil, and vanilla extract to the yolk mixture and mix well.

Sift in the dry ingredients (cake flour, cocoa powder, baking powder) and mix until just combined.

In a separate bowl, whip egg whites while gradually adding sugar until stiff peaks form.

Fold the meringue into the batter in three additions, using a spatula to gently combine.

Fill muffin cups 70–80% full, tap lightly to remove large air bubbles, and bake at 170°C for 20 minutes.

Immediately invert the cupcakes after baking and let them cool completely.

[Chocolate Whipped Cream] Whip heavy cream and sugar to 60% stiffness, then add melted chocolate and whip until firm.

Transfer the whipped cream to a piping bag fitted with a round tip.

Use a chopstick to create a hole in the center of each cupcake.