Step 1

Preheat the oven to 350°F / 180°C with a rack in the center. Butter and flour a 9-inch / 8-cup bundt pan, or equivalent*. See head note.

Step 2

Sift together the flour, sugar, cocoa powder, baking powder, baking soda, and salt in a large bowl. In a medium bowl whisk together the eggs, milk, and vanilla extract. Mix in the melted butter. Pour the wet mixture over the dry ingredients and stir until uniform. Add the coffee and stir until the batter is smooth. Pour the batter into your prepared pan and bake for 45-50 minutes, or until a cake tester comes out clean. Leave the cake to rest for ten minutes, and turn out onto a rack to cool completely.

Step 3

Whisk together the powdered sugar, salt, vanilla extract, and tahini. Add 2 tablespoons of the buttermilk, and stir until smooth and thick. Add another tablespoon, or so, if needed to get the icing to a consistency you like - not so thick that it won’t spread down the cake, or so thin it runs right off. Somewhere between.

Step 4

When the cake has cooled completely, slowly pour the icing over the cake, and allow it to set for ten minutes or so. If you have the cake on a cooling rack, set over a rimmed baking sheet, you can avoid any mess.