Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan with butter or cooking spray. Line the bottom with parchment paper for easy removal.
In a large mixing bowl, whisk together the flour, cocoa powder, sugar, baking powder, baking soda, and salt until well combined.
Add the eggs, buttermilk, vegetable oil, and vanilla extract to the dry ingredients. Mix until the batter is smooth and no lumps remain.
Slowly pour in the hot water and stir until the batter becomes glossy and well incorporated.
Pour the batter into the prepared cake pan and smooth the top with a rubber spatula.
Bake the cake in the preheated oven for approximately 35-40 minutes or until a toothpick inserted into the center comes out with a few moist crumbs clinging to it.
While the cake is baking, prepare the ganache by heating the heavy cream in a saucepan over medium heat until it simmers. Remove from heat and add the chocolate chips. Stir until the chocolate is completely melted and the mixture is smooth.
Once the cake is done baking, let it cool in the pan for 10 minutes. Then, transfer it to a cooling rack to cool completely.
Pour the ganache over the cooled cake, allowing it to drizzle down the sides for a stunning finish.