Preheat oven to 175°C (350°F). Grease and flour your cake tin.

Whisk eggs and sugar until light and foamy.

Add milk, oil, vanilla, and lemon zest. Mix well.

Sift flour, cocoa powder, baking powder, and salt in another bowl.

Add dry ingredients to wet. Mix until just combined.

Stir in hot water or coffee for a smoother batter.

Pour into pan, tap to release air bubbles.

Bake 30–35 min, until a toothpick comes out clean.

Cool before removing from pan.