Combine banana, ½ cup brown sugar, butter and rum extract in a sauce pan. Cook over medium heat until mixture starts to bubble, stirring constantly.
Remove from heat and pour into a large bowl.
Once cooled, add Amish Friendship Bread starter, the remaining ½ cup brown sugar and egg. Mix thoroughly until well incorporated.
In a small bowl, combine flour, baking soda, salt, cinnamon and allspice. Add flour mixture to banana mixture and beat until just blended. Pour batter into greased pans.
Bake for about 50-60 minutes or until a toothpick inserted comes out clean. Let cool then drizzle with Rum Glaze.