To prepare the cake, using an electric mixer combine sugar, eggs, vegetable oil, vanilla, milk and lemon zest at medium speed.

When well combined, add the flour, baking powder and cocoa powder and mix again on low speed for 3 minutes. Allow batter to rest for five minutes.

Pre-heat oven at 200 degree (medium heat).

Pour the batter in a grease baking tray and place it oven for 35 minutes.

Remove cake from oven and set aside to cool.

To prepare the chocolate sauce, in a saucepan mix the milk, sugar, and cocoa powder.

Place on medium heat then add the butter. Stir until the sauce starts to thicken. Remove from heat and allow sauce to cool.