Preheat oven to 350°F. Grease and flour a bundt pan. Set aside.

Sift the flour, cocoa powder, baking powder, baking soda, and salt into a medium-sized bowl and whisk until well combined. Set aside.

In a large bowl, cream the butter on medium speed with a handheld electric or stand mixer for 2 minutes. Add the sugars and cream on medium speed for 2 more minutes. Add the eggs one at a time, mixing until combined. Add the vanilla and mix until combined.

Add 1/3 of the flour mixture into the butter mixture and mix on low speed until mostly combined. Add 1/2 of the buttermilk and mix. Add another 1/3 of the flour mixture, again mixing until mostly combined. Add the rest of the buttermilk and mix. Finally, add the rest of the flour mixture and mix on low until just combined. 

Fold in the chocolate chips, and pour batter into prepared bundt pan. Use a spatula to even out the top, and tap the pan on the counter to release any air bubbles. Bake at 350°F for 40-45 minutes, or until a toothpick inserted into the cake comes out clean.

Let the cake cool in the bundt pan for 10-15 minutes. Then, transfer to a cooling rack or cake stand and let cool completely.

Make the chocolate glaze while the cake is cooling. To make the chocolate glaze, place the chopped chocolate and butter in a medium-sized bowl and microwave in 30-second intervals until melted, whisking in between each interval. Pour the glaze over the cooled cake while the glaze is still warm.