Step 1

Preheat oven to 350°F / 180°C, with a rack in the center.

Step 2

Butter and flour (generously) a 11 or 12-cup capacity bundt pan (or equivalent). As I mention up above, you can bake this in other cake pans, just be mindful to avoid filling the pan(s) more than 2/3 - 3/4 full. Adjust the baking time as well, baking until the cake begins to pull away from the sides of the pan, and the center tests clean when you insert a knife.

Step 3

In a saucepan over medium heat, simmer the beer down to 1 cup / 240 ml, it will take 15 minutes or so. Remove from heat, add the butter and stir until melted. Stir in the cocoa powder, mixing until smooth, then set aside to cool, stirring occasionally to release heat.

Step 4

In a medium bowl, whisk together the flours, sugar, baking soda, and salt. Set aside.

Step 5

In a large mixing bowl, combine the eggs, yogurt, and maple syrup. Whisk well, until nicely blended and uniform in appearance. Gradually add the (cooled) stout mixture, stirring all the while. Stir until well blended. Add the flour mixture, folding until just blended, using as few strokes as possible, a few lumps in the batter are fine.

Step 6

Transfer the batter to the prepared pan and bake for 35 - 45 minutes if using the bundt pan, or until a knife inserted in the center comes out clean. You really don't want to over bake this cake - err on the slightly moist side if anything. Remove from the oven, allow to cool for ten minutes or so, and turn out onto a cooling rack.

Step 7

In the meantime, make the icing by whisking together the powdered sugar, cocoa, and buttermilk. Really go at it for at least a minute. The icing should end up smooth and creamy looking, adjust with a touch of powdered sugar or a few extra drops of buttermilk if you want to tweak the consistency at all. When the cake is completely cool, run the icing around the top with an offset spatula and let it set.

Step 8

Serve sprinkled with a bit of flaky sea salt. But don't sprinkle with flakes of salt until ready to serve, or you'll end up with little divots (see photos :).