Preheat your oven to 350°F (175°C) and grease two 9-inch round cake pans.
In a large bowl, combine flour, sugar, cocoa powder, baking powder, baking soda, and salt.
Add eggs, milk, oil, and vanilla extract to the dry ingredients and mix until smooth.
Carefully mix in boiling water until the batter is well combined.
Pour the batter evenly into the prepared cake pans.
Bake for 30-35 minutes, or until a toothpick comes out clean.
Allow the cakes to cool in the pans for 10 minutes before transferring to wire racks.
For the ganache, heat heavy cream in a saucepan until just boiling.
Pour the hot cream over the chopped chocolate and let it sit for 5 minutes, then stir until smooth.
Spread ganache between the layers and over the top and sides of the cake.