Preheat the oven to 350ºF. Grease and flour a 9x5-inch loaf pan, or line with parchment paper.

In a small bowl, mix together the cocoa powder and hot coffee until the cocoa powder has dissolved.

In another bowl, whisk together the flour, baking powder and salt.

In the bowl of a mixer, cream together the butter and sugar until light and fluffy, about 3 minutes. Add in the eggs one at a time, mixing for 1 minute after each addition. Mix in the vanilla. Add in the flour mixture and mix just until combined. Very carefully mix in the coffee/chocolate mixture until combined. Add in the buttermilk, then fold in the chocolate chips. Pour the mixture into the prepared loaf pan and smooth the top.

Bake in the preheated oven until a tester inserted in the center comes out clean, 50-60 minutes. Allow the cake to cool for 20 minutes, then turn out onto a cooling rack to cool completely.

Meanwhile, to make the glaze, sift together the powdered sugar and cocoa powder. Stir in the salt and then the vanilla. Whisk in 2 tablespoons of milk, then continue to add the liquid until the glaze reaches the desired consistency.

When the cake is cooled, pour the glaze over the top of the cake. Let the cake sit for 30 minutes before cutting and serving.