Preheat your oven to 325°F (163°C). Grease and flour a 12-cup bundt pan.
In a bowl, whisk together the flour, baking powder, baking soda, salt, and sifted cocoa powder.
In the bowl of your mixer, beat the softened butter on medium speed until smooth. Gradually add sugar and beat for 3-5 minutes until light and fluffy.
Add eggs one at a time, mixing well after each addition.
Mix the vanilla extract into the buttermilk.
Gradually add the dry ingredients alternately with the buttermilk, beginning and ending with the dry ingredients. Mix until just incorporated.
Gently fold in the mini chocolate chips.
Pour the batter into the prepared bundt pan and bake for 50-55 minutes, or until a toothpick comes out clean. Allow the cake to cool for 10 minutes in the pan before transferring to a wire rack to cool completely.
For the glaze: Microwave butter, chocolate chips, and corn syrup in 20-second intervals, stirring between each, until smooth.
Drizzle the glaze over the cooled cake and allow it to set before serving.