Preheat oven to 350 degrees F (175 degrees C). Lightly grease 9x9 inch baking pan.
In a large bowl, stir together oats, flour, baking powder, cinnamon and salt. In a separate bowl, cream together brown sugar and margarine. Beat in egg. Stir mixtures together just until blended. Pour batter into prepared pan.
Bake in preheated oven for 30 minutes, until a toothpick inserted into center of pan comes out clean.