In a small bowl combine quick cooking oats with sour milk. Blend well; let stand 1 hour.
Sift together flour, baking powder, baking soda, and salt; set aside.
In a mixing bowl cream together butter and brown sugar; add egg beating until light and fluffy. Add dry ingredients alternately with the oatmeal mixture to the creamed mixture, blending well after each addition. Spoon batter into greased muffin tins, filling two-thirds full.
Bake in a 400*F oven for 20 minutes, or until golden brown. Remove from oven. Let cool completely.