In a large pot, bring 1 cup of Guinness stout or oatmeal stout and 1 cup of dark molasses to a boil over medium heat. Whisk in 1 teaspoon of baking soda and set aside to cool.

Preheat your oven to 350°F (175°C) and prepare a 10-inch bundt pan with baking spray and flour.

In a mixing bowl, whisk together 2 cups of flour, 2 teaspoons of baking powder, and spices until combined.

In another bowl, whisk 2 eggs, 0.5 cup dark brown sugar, and 0.5 cup granulated sugar. Add 0.5 cup vegetable oil and 2 tablespoons freshly grated ginger.

Gradually blend the stout mixture into the egg and sugar mixture, whisking continuously.

Fold the dry ingredients into the wet mixture until just combined, avoiding overmixing.

Pour the batter into the prepared pan and tap lightly on the counter.

Bake for 50-60 minutes; check doneness with a toothpick.

Let the gingerbread cool in the pan for 15 minutes before inverting onto a wire rack.

Dust with powdered sugar and serve with whipped cream if desired.