Preheat oven to 350F.
Spray a 9x5 inches loaf pan with baking spray. Set aside.
In the bowl of an electric mixer whisk on low flour, sugar, salt and baking powder until combined. If using cocoa powder instead of food coloring, add it now. With the mixer on low medium speed, add the almond milk and oil, mix until combined. Add the mashed banana and whisk until all combined. Fold in the sprinkles.
Transfer 1/3 of the batter to the loaf pan, top with the Batman shapes, and starting 1 inch away from the loaf wall. Stack the Batman shapes one after each other; you need to leave 1 inch room for the loaf pan at the start and end. Pour the rest of the batter over the Batman shapes.
Bake for 40 - 45 minutes or until a cake tester inserted into the cake comes out clean. I usually test at the beginning and end of the cake where there is little space with no Batman shape. The cake must be golden brown.
Remove cake from oven; let it cool in the pan for 10 - 15 minutes before transferring to a wire rack to cool completely.
Once the cake has cooled, work on the glaze. Combine powdered sugar with 1 tablespoon of almond milk at a time until no lumps are visible. If the mixture is too thick add a little more milk until the right, pourable consistency has been achieved. Poor the glaze over the cake and top with sprinkles. Let the glaze settle, slice the cake and serve.