Preheat oven to 200°C. Grease a 21x11cm 1.5L cake tin.
Whisk together flour, oatmeal and baking powder in a large bowl. Add beer and stir until dry ingredients are wet.
Pour the dough into the mold and smooth out. Make a groove in the center. Bake for 35-40 minutes or until a toothpick inserted in the center of the bread comes out dry. Cool the bread on a wire rack for 5-10 minutes, then remove from the mold and cool completely.