Gingerbread Stout Cake

Adjust oven rack to the middle position and preheat oven to 350 degrees F. Grease and flour an 8-inch square baking pan.

Bring stout to a boil in a medium saucepan over medium heat, stirring occasionally. Remove from heat and stir in baking soda (mixture will foam vigorously). When foaming subsides, stir in molasses, brown sugar, and granulated sugar until dissolved; set mixture aside.

Whisk flour, ground ginger, baking powder, salt, cinnamon, and pepper (optional) together in a large bowl; set aside.

Transfer stout mixture to a large bowl. Whisk in eggs, oil, and granulated ginger until combined. Whisk wet mixture into flour mixture in thirds, stirring vigorously until completely smooth after each addition.

Transfer batter to prepared pan and gently tap pan against counter 3 or 4 times to dislodge any large air bubbles. Bake until the top of the cake is just firm to touch and a toothpick comes out clean, 35 to 45 minutes. Cool cake in the pan on a wire rack, about 1 1/2 hours. Cut into squares and serve warm or at room temperature.