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

In a large mixing bowl, combine all-purpose flour, unsweetened cocoa powder, granulated sugar, baking powder, baking soda, and salt; whisk until free of lumps.

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

Stir in hot coffee until fully incorporated.

Divide the batter among the prepared cake pans and bake for 25-30 minutes.

For the orange filling, whisk together sugar, cornstarch, and egg yolks; gradually whisk in orange juice and cook over medium heat until thickened.

Mix in the orange zest and butter until smooth.

Heat heavy cream until steaming, pour over chopped dark chocolate, let sit, then stir until smooth to make ganache.

Allow cake layers to cool completely, then assemble with orange filling between layers and pour ganache on top.

Garnish as desired and let set before serving.