Boil the potatoes until soft; drain. Add butter and let melt over hot potatoes. Mash potatoes and add cream, mixing until smooth and not stiff. Add cayenne pepper, garlic powder, parsley, green onions, and cheese to the potatoes. Fold in crabmeat.
Place mixture in a casserole dish or individual ramekins and sprinkle with paprika. Bake at 400 degrees until heated through and cheese melts, about 20 to 25 minutes in a casserole dish or 15 to 20 minutes in a ramekin. Casserole serves 8 to 10.