Preheat oven 350°F. Add brown sugar, butter, and flour into a bowl. Mix well and press evenly into ungreased 13x9-inch pan. Bake at 350°F for 10 minutes.
As that bakes, in another bowl, add eggs, vanilla, sugar, mashed banana, oil and canned sweet potatoes. Whisk together and combine flour, salt, baking soda, baking powder, and cinnamon. Add slowly to wet ingredients, mix well. Add filling to baked crust. Spread evenly and bake for 20 minutes. Cool for 1 hour.
Melt Baker's White Chocolate in microwave oven for 1 minute or until smooth. Drizzle over bars. Store at room temperature, or in refrigerator (it will be harder to cut through). Cut into squares and enjoy.