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

Melt dark chocolate in a heatproof bowl using a microwave or double boiler until smooth. Allow to cool slightly.

Beat unsalted butter with granulated and light brown sugars until fluffy, about 3 minutes, until creamy and light in color.

Add eggs one at a time while mixing. Stir in vanilla extract until the batter looks smooth and rich.

Fold in the cooled, melted chocolate into the wet mixture until fully combined.

In another bowl, whisk all-purpose flour, cocoa powder, baking soda, baking powder, espresso powder, and salt.

Gradually add the dry mixture to the wet mixture, alternating with buttermilk. Start and finish with the dry ingredients.

Gently fold in semi-sweet chocolate chips for added richness throughout the batter.

Divide batter between prepared pans and bake for 30-35 minutes, testing with a toothpick for moist crumbs.

Let cakes cool in the pans for 10 minutes before inverting onto wire racks to cool completely.

Heat heavy cream until simmering, pour over chopped chocolate, and stir until smooth to make the ganache.

Spread ganache between layers of cakes and pour remaining ganache on top, allowing it to drip down the sides.