Microwave chocolate and nutella for 1 min, stir until melted. Cool.
In a separate bowl mix the flour, baking soda, and salt; set aside. Beat eggs in medium bowl, stir in melted chocolate, brown sugar, buttermilk, 1/2 cup oil and the banana. Add to the flour mixture, stir just until moistened. Stir in 2 cups of the cereal. Spoon batter into greased 9×5-inch loaf pan. Crush remaining 1/2 cup cereal in small bowl and add 1 tsp oil; mix well. Sprinkle evenly over batter.
Bake 50-55 min or until toothpick inserted comes out clean. Cool 10 minutes; remove from pan. Cool completely on wire rack.