Preheat the oven to 325F degrees. Line a 9x5” loaf pan with parchment paper and grease lightly with butter or non-stick spray.
In a large bowl, combine the whole wheat flour, all-purpose flour, baking powder, baking soda, baking powder, and salt. Make a well in the center.
In a separate bowl, whisk together the beer, buttermilk, molasses, and egg. Pour the wet ingredients into the well.
With your fingers or a spatula, stir the batter from the middle of the bowl to the outside, until it's well mixed. It will look more like cake batter than bread dough. Spoon the dough into the prepared pan. Sprinkle the oats on top.
Bake until deep golden brown and instant-read thermometer reads 200oF, about 1 hour to 1 hour 5 minutes. Let cool in pan for 15 minutes. Remove from pan; wrap in a clean towel and let cool on a wire rack. Best served warm.