The Great Chocolate Stout Cake Experiment v1.0
1/3 cup mild molasses and dark corn syrup
7-1/2 oz. (1-2/3 cups) all-purpose flour
2-1/4 oz. (3/4 cup) unsweetened natural cocoa powder (not Dutch-processed); more for the pan
1-1/2 tsp. baking powder
1/2 tsp. baking soda
1/2 tsp. salt
10 oz. unsalted butter, at room temperature
1-1/2 cups packed brown sugar (or white sugar)
3 large eggs, at room temperature
1/3 cup sour cream
6 oz. semisweet chocolate, very finely chopped (pulsed in a food processor works well)
In a microwave, bring the stout and molasses to a simmer (note: I don't really see the need for this step, but did it anyway). Dissolve the baking soda in the mixture and let cool while preparing the cake batter.
Sift together the flour, cocoa powder, baking powder and salt. With a stand or hand mixer, cream the butter in a large bowl on medium speed until smooth, then add the brown sugar and beat on until light and fluffy, about 3 minutes. Stop to scrape the sides of the bowl as needed. Beat in the eggs one at a time, stopping to scrape the bowl after each addition. With the mixer on low speed, alternate adding the flour and stout mixtures, beginning and ending with the flour. Stop the mixer at least one last time to scrape the bowl and then beat at medium speed until the batter is smooth, about 20 seconds. Fold in the sour cream and finely chopped chocolate.
Spoon the batter into the prepared pan, spreading it evenly with a rubber spatula and wiggling the pan to level the batter. Bake until a skewer inserted in the center comes out nearly clean, 50-60 minutes. Set the pan on a rack to cool for 20 minutes. Say a prayer to the cake gods and invert the cake onto the rack and remove the pan. Without crying, remove the stuck parts out of the pan and press back onto the cake as decoratively as you can. Let cool until just barely warm, then wrap tightly in plastic wrap if not serving right away; if serving, sift powdered sugar over the top if the cake is pretty; if it's a wreck (and it probably is), opt to drizzle a lot of ganache over the whole thing.