Preheat oven and prepare cake pan: Preheat your oven to 350 F degrees. Spray a 10 inch angel food cake pan with cooking spray. Set aside.
Combine dry ingredients: In a large bowl combine the flour, baking soda, baking powder, salt, walnuts and chocolate chips.
Combine wet ingredients: In another medium bowl mash the bananas using a fork or a potato masher. Add the sour cream, eggs, applesauce, vanilla extract and granulated sugar and whisk everything together.
Combine wet and dry: Pour the wet ingredients into the bowl with the flour and using a spatula mix everything together.
Prepare filling: In another small bowl combine all the filling ingredients together.
Assemble cake: Spread 1/3 of the batter into the prepared cake pan. Sprinkle 1/3 of the filling over the batter and repeat 2 more times to finish the rest of the batter and filling.
Bake: Place the cake pan in the oven and bake for about 1 hour or until a toothpick inserted in the center comes out clean. Cool the cake in the pan for 10 minutes then remove and continue cooling on a wire rack.
Make glaze: Meanwhile, make the glaze by whisking all the ingredients together in a small bowl, adding more milk if needed. The glaze should be smooth and thin enough to drizzle.
Drizzle with glaze, cut and serve: Drizzle the glaze over the cake, cut into slices and serve.