Preheat the oven to 350 degrees and generously butter and flour your bundt pan, knocking out the excess flour.
In a medium saucepan, combine the stout beer and dark molasses. Bring to a boil and remove from heat. Add in the baking soda and stir to combine. The mixture will bubble up, stir gently to keep it from overflowing. Allow the mixture to return to room temperature.
In a large bowl, sift together the flour, baking powder and spices. Set aside.
In the bowl of a stand mixer with the paddle attachment, mix the eggs, sugars and vanilla extract on medium speed until well combined. Add the oil and then the molasses mixture. Reduce the speed to low and add in the flour mixture. Mix until just combined. Pour the batter into the bundt pan and give it a tap on the counter to remove air bubbles.
Bake 50-55 minutes until a toothpick inserted into the cake comes out mostly clean.
Allow the cake to cool on a rack for about 5 minutes and then remove it to a plate and allow to cool completely. Dust with powdered sugar and enjoy!
This gingerbread keeps well and is even better the next day!