In a large skillet, cook beef over medium heat until meat is no longer pink; drain. Stir in taco seasoning and water. Bring to a boil. Reduce heat and simmer for 5 minutes. Stir in beans.
Spoon meat mixture into a greased 8-in. square baking dish. Sprinkle with Monterey Jack cheese. In a large bowl, combine the eggs, milk and biscuit mix until moistened. Pour over cheese.
Bake, uncovered, at 400° for 20-25 minutes or until lightly browned and a knife inserted near the center comes out clean. Spread with sour cream. Top with cheddar cheese, lettuce, tomato and olives. Yield: 6-8 servings.