01 -
Preheat the oven to 350°F. Spray a 9x5-inch loaf pan with nonstick cooking spray and line it with parchment paper with a 2-inch overhang on two sides.
02 -
In a large bowl, whisk together granulated sugar, eggs, stout beer, vegetable oil, vanilla extract, and instant coffee granules until smooth and fully combined, about 2 minutes.
03 -
Set a fine-mesh strainer over the bowl and sift all-purpose flour, cocoa powder, baking powder, baking soda, and salt into the wet ingredients. Gently tap until fully incorporated then whisk until only a few streaks of flour remain.
04 -
Pour the boiling water into the batter and whisk until smooth. The batter will be thin. Scrape into the prepared loaf pan.
05 -
Bake for about 55 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs but no wet batter.
06 -
Remove the pan from the oven and let the cake cool completely on a wire rack, approximately 1 hour.
07 -
In a small bowl, whisk powdered sugar, Baileys Irish Cream or heavy cream, and a pinch of salt until smooth and creamy. Adjust consistency by adding powdered sugar or cream as needed to achieve a molasses-like texture.
08 -
Lift the cooled cake from the pan using the parchment paper overhang and place on a serving platter. Pour the glaze over the top, spreading evenly. Sprinkle with shaved dark chocolate if desired. Allow glaze to set for 10 to 15 minutes before slicing and serving.