Preheat oven to 400F. Lightly oil or spray a 2-3 quart casserole dish.
Heat a non-stick pan over medium-high heat. Give it a quick spray of oil, if desired, and add the onions. Cook until onions soften, 2-3 minutes. Add the celery, mushrooms, and garlic and cook for 2-3 more minutes, until mushrooms exude their juices. Add the asparagus and two tablespoons of vegetable broth, cover pan, and cook for another 2-3 minutes, until asparagus is bright green and beginning to become tender.
Whisk the flour into the cup of vegetable broth. Add it, the milk, nutritional yeast, thyme, and basil and heat until bubbly. Add the chickpeas and salt and pepper to taste. Turn heat to low, and simmer for 5 minutes. Pour into prepared casserole dish and top with an even layer of potatoes. Sprinkle potatoes with salt, if desired, and smoked paprika.
Bake until casserole is bubbly and top is lightly browned, 25-45 minutes (frozen potatoes will take longer than fresh). If top does not completely brown, place it under the broiler for a few seconds.