Adjust your oven rack to the lower third of the oven and preheat to 325°F. Generously grease and flour a 12-cup bundt pan to prevent sticking.

In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt. Set aside.

In the large bowl of a stand mixer, beat the softened butter on medium speed until it becomes creamy and smooth. Gradually add in the sugar, continuing to beat for about 3-5 minutes, until the mixture turns light and fluffy. Be sure to scrape down the sides and bottom of the bowl occasionally to ensure even mixing.

Add the eggs, one by one, ensuring each egg is fully incorporated before adding the next. Continue mixing until the yolks are fully blended.

Combine the vanilla extract with the buttermilk and set aside.

Gradually add the dry ingredients to the butter mixture, alternating with the buttermilk. Start and finish with the dry ingredients—add in 3 portions of the dry mixture, and 2 portions of the wet. Mix just until each addition is incorporated, taking care not to over-mix. Fold in the mini chocolate chips if using.

Pour the batter evenly into the prepared bundt pan. Bake for 50-55 minutes or until a toothpick inserted into the center comes out clean or with a few crumbs. Dark-colored bundt pans tend to shorten baking time, while lighter-colored pans may require a few extra minutes.

Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.

In a microwave-safe bowl, combine the mini chocolate chips, butter, and corn syrup. Microwave on high for 20 seconds, then stir. Repeat for another 20 seconds, stir again, and microwave for an additional 5 seconds. Stir until the mixture is completely smooth and glossy.

Drizzle the glaze over the cooled cake, allowing it to flow over the edges for a beautiful finish. Let the glaze set before slicing and serving.