Preheat oven to 350 degrees F. In a mixing bowl, combine the flour, baking powder, 1/2cup oats, brown sugar, and salt. Slowly add the Guinness and mix until combined.
Coat loaf pan with cooking spray and our the batter into the pan. Sprinkle the top with additional tablespoon of oats. Place into the center of the oven and bake for 45-50 minutes. When bread is done, you should be able to insert a knife and it come out clean. Allow to cool for 15 minutes before removing from the pan.