Step By Step

Instructions

Prep work
Whip the eggs and sugar together
Crack your room temperature eggs right into a deep mixing bowl along with the granulated sugar. Grab your hand mixer and whip them on high speed until the sugar is fully dissolved and the mixture turns thick, pale, and ribbony. You are looking for the volume to roughly double, which sets up a light, airy base for the cake.
3 large eggs7 oz granulated sugarLarge mixing bowlHand mixer
Stir in the wet ingredients
Go ahead and switch off the mixer for a second. Pour in the whole milk, sunflower oil, and vanilla extract directly with the whipped eggs. Give it a gentle spin on low speed just until the liquids come together cleanly without knocking out too much air.
1 cup whole milk1/4 cup sunflower oil1 tsp vanilla extractHand mixer
Sift and combine the dry ingredients
Balance your fine mesh sieve over the bowl and sift the cocoa powder, baking powder, and all-purpose flour right on top. Mix gently on your lowest setting, turning off the beaters the second you get a smooth, uniform batter. Try not to overwork it here, or the crumb will end up dense instead of fluffy.
1 oz unsweetened cocoa powder10 g baking powder5 oz all-purpose flourFine mesh sieveHand mixer
Baking
Bake the cake
Transfer your batter into a greased 9-inch square heatproof baking dish. Slide it onto the middle rack of an oven preheated to 350F (180C), sticking to the regular bake setting rather than convection. Let it bake for around 30 minutes until a toothpick poked into the middle comes away clean, keeping the oven door shut for at least the first 20 minutes so it doesn't sink.
1/4 cup sunflower oil9-inch square baking dishToothpick
Finishing touches
Simmer the chocolate sauce
As the sponge hits its last few minutes in the oven, combine the whole milk, granulated sugar, sunflower oil, cocoa powder, and salt in a medium saucepan. Keep whisking steadily over medium heat until the mixture comes to a full, rolling boil, then pull it off the heat immediately.
1 cup whole milk7 oz granulated sugar1/4 cup sunflower oil1 oz unsweetened cocoa powder3 g saltMedium saucepan
Drench the warm cake
Take the cake straight out of the oven. To get that rich syrup to soak down deep into every bite, either slice the hot cake into squares right away or prick it all over with a toothpick. Slowly ladle that bubbling hot chocolate sauce evenly across the entire surface while everything is still piping hot.
Toothpick
Let it soak and garnish
Leave the cake alone on the counter for at least 1 to 2 hours so it can pull in all the syrup and let those deep chocolate notes settle. Right when you are ready to plate it up, scatter sliced almonds over the top to add a nice, delicate crunch.
15 g sliced almonds

You will want to pour the hot chocolate syrup right over this cocoa sponge as soon as it pulls out of the oven. Make sure to poke plenty of holes across the top first so all that goodness sinks straight into the center, and give it plenty of patience to soak in before cutting a slice.

Because this is an oil-based sponge, it stays tender even if you keep it in the fridge. Be sure to sift your dry ingredients and keep an eye on your bake time so the crumb stays light enough to drink up the sauce. If you see the liquid start pooling, just take your time and pour it in batches so every drop absorbs.