Preheat the oven to 350°F (175°C) and prepare three 8-inch round cake pans by greasing and lining them with parchment paper.

In a large mixing bowl, combine flour, cocoa powder, sugar, baking powder, baking soda, and salt. Whisk together for about a minute.

Add eggs, milk, oil, and vanilla extract to the dry mixture and mix until smooth and uniform, about 2-3 minutes.

Carefully stir in the hot coffee until well combined.

Divide the batter among the prepared pans and bake for 25-30 minutes, until a toothpick inserted comes out clean.

Cool cakes in pans for 10 minutes before transferring to wire racks to cool completely.

For the filling, whisk sugar, cornstarch, and egg yolks in a saucepan. Gradually add orange juice and stir over medium heat until thickened, about 5-7 minutes, then stir in zest and butter.

For the ganache, heat cream until simmering, pour over chopped chocolate, let sit for 5 minutes, then stir until smooth.

To assemble, layer cake, spreading orange cream filling between layers, finishing with the final cake layer.

Pour warm ganache over the top of the cake and let it drip down the sides. Smooth out if necessary and let set before garnishing.