Preheat oven to 450 F. Combine black bean powder with 3 C boiling water. Stir in the chili powder, cumin, salt, and garlic powder, then cover and set aside for 5 minutes. In a separate bowl, mash the avocado with lime juice and a pinch of salt then set aside. Spread the beans into the bottom of a 9 X 13 baking dish or a large cast iron skillet. Top the beans with the shredded cheese and bake just until cheese is melted and bubbly. Remove from oven and allow to cool slightly. Layer on the mashed avocado, sour cream, and salsa, then sprinkle with olives, scallions, and cilantro. Serve with chips for dipping.