In a large bowl, combine oats and buttermilk; let stand 5 minutes. Stir in eggs. Combine flour, brown sugar, baking powder, cinnamon and baking soda; stir into oatmeal mixture just until moistened. Fill greased or paper-lined muffin cups two-thirds full. Bake at 400 degrees F for 18-20 minutes or until muffins test done. Cool in pan 10 minutes before removing to a wire rack.
P.S. You can add/sneak any fruit or nuts you'd like to these, I might even try shredded carrots next time <3