Preheat the oven to 375 degrees. Lightly mist a 9x13 casserole dish with cooking spray and set aside.
Place the butter in a medium saucepan and bring over medium-low heat until the butter is melted. Add the flour, ½ teaspoon of the salt and the black pepper to the butter and stir to combine. Add the milk a little at a time and whisk the flour mixture into the milk each time until smooth. Turn the heat up to medium and add the shredded cheeses. Whisk together and then whisk on and off for about 5 minutes until smooth and thickened. Stir in the Buffalo wing sauce.
Combine the drained, rinsed chickpeas and the chicken in the prepared casserole dish and pour the cheese sauce from step 2 over the top. Stir it all together until well combined and settled into an even layer in the casserole dish.
Spread the bread crumbs in a dry medium skillet and bring over medium heat. Keep an eye on the bread crumbs for a few minutes, pushing them around with a spatula every few minutes until they start to turn golden. They go from lightly golden to dark brown quickly, so keep your eyes peeled! When the crumbs are golden, remove them from the heat and combine them with the remaining ¼ teaspoon of salt, the parsley and the garlic powder.
Sprinkle the bread crumb mixture over the top of the contents of the casserole dish and place the dish in the heated oven. Bake for 40-45 minutes until baked through and bubbly.