Preheat your oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
Add the buttermilk, vegetable oil, eggs, and vanilla extract to the dry ingredients. Mix until just combined.
Carefully pour in the boiling water and stir until the batter is smooth.
Pour the batter into the prepared baking pan. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes before inverting it onto a wire rack to cool completely.
Place the chocolate chips in a heatproof bowl. In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer.
Pour the hot cream over the chocolate chips and let it sit for 1 minute to soften the chocolate.
Gently stir the chocolate and cream together until the chocolate is completely melted and the ganache is smooth and glossy.
Once the cake is completely cooled, pour the ganache glaze over the top, allowing it to drip down the sides.
Let the ganache set for about 30 minutes before slicing and serving.