Preheat your oven to 350°F (175°C) and prepare two 9-inch round cake pans by greasing or lining them with parchment paper.

In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.

Add the eggs, milk, vegetable oil, and vanilla extract to the dry mix. Beat everything together on medium speed for about 2 minutes until smooth.

Stir in the boiling water (the batter will be thin) and pour it into the prepared cake pans.

Bake for 30-35 minutes or until a toothpick inserted in the center comes out clean. Let them cool in the pans for 10 minutes before transferring to a wire rack to cool completely.

In a medium saucepan, combine the cornstarch and sugar. Slowly whisk in the milk until smooth. Heat over medium, stirring until it bubbles and thickens.

In a separate bowl, whisk together the egg yolks, orange zest, and juice. Gradually whisk in some of the hot milk mixture into the egg yolks, then return everything to the saucepan.

Cook for an additional 2 minutes, stirring continuously. Remove from heat and stir in the vanilla. Let it cool.

Once the cake layers are cool, place one layer on a serving platter. Spread a layer of orange custard on top, then add the second layer and repeat. Chill in the fridge for at least 30 minutes.

Heat the heavy cream until just boiling, then remove from heat and add the chopped chocolate. Let it sit for a couple of minutes, then stir until smooth.

Pour the ganache over the cake, allowing it to drip down the sides, and garnish with a sprinkle of orange zest.