Preheat your oven to 325°F. Liberally prepare a 12-cup Bundt pan with the nonstick method of your choice.
Pour the chocolate chips into a medium microwave-safe bowl. Microwave on high for 15 seconds at a time, stirring after each heating interval, until the chocolate is melted.
In the bowl of your stand mixer fitted with the whisk attachment, beat the butter for 2 minutes on high speed. Slowly add the granulated sugar. Cream together for an additional 5 minutes, until very pale yellow and fluffy. Add the eggs 1 at a time, combining well after each addition and scraping down the sides and bottom of the bowl as needed.
Turn your mixer down to its lowest speed and slowly add the flour in 2 batches. Be careful not to overbeat. Add the cocoa powder, coffee powder, baking powder, and salt. Lastly, add the melted chocolate, buttermilk, and vanilla extract. Make sure the chocolate cools slightly so as to not curdle the buttermilk. Scrape down the sides and bottom of the bowl and mix the batter until just combined. Be careful to not overmix.
Pour the batter into the prepared pan and bake for 70 to 80 minutes, or until a toothpick inserted into the center of the cake comes out clean. Check frequently to ensure you do not overbake this cake.
Let the cake cool in the pan on a wire rack for 10 minutes, then invert onto a serving plate. Let cool to room temperature. Lightly cover the cake with foil or plastic wrap so it does not dry out.