Preheat oven to 350 degrees F. Coat a loaf pan generously with non-stick cooking spray.
In a medium bowl, stir together the flour, baking soda, and salt. Set aside.
In a large bowl, beat together sour cream, applesauce, and eggs until well combined. Add vanilla and brown sugar; mix to combine.
Add flour mixture to sour cream mixture, and mix until just combined.
Stir in oats and chocolate by hand. Pour bread batter into prepared loaf pan.
Bake for 40 minutes. After 40 minutes, place a piece of tin foil over the top of the bread to prevent over-browning and bake for an additional 15 minutes, or until a toothpick inserted in the center comes out clean.
Remove from the oven and cool completely on a wire rack.
Frosting:
Simmer 1 to 2-inches of water in a medium saucepan. Place a glass or metal bowl over the simmering water to create a double boiler.
Place the chocolate in the bowl, and stir occasionally until melted and smooth.
Put sour cream in a medium mixing bowl. Pour warm chocolate over the sour cream and stir together until well combined and mixture sets up into a frosting-like consistency. (If the frosting is too loose, place the bowl in the fridge to let it cool and set up.)
Spread frosting over the top of the bread, if desired. You'll probably have extra frosting.