Preheat the oven to 400 F. Mash the beans with one-half cup of the picante until well mixed. Grease two 9" x 13" baking pans. Place half the chips in each pan, then spoon the bean mixture over them. Sprinkle the grated cheese on top. Bake for about minutes or until the cheese is melted and beans are bubbling.
Meanwhile, peel, pit and mash the avocado, then mix it with the lemon juice, 1/2 cup of the sour cream, the grated onion, and 1 tablespoon of the picante. Garnish the nachos with the guacamole you just made, the remainder of the sour cream, scallions, tomato, and olives.