Combine the refried beans, rotel diced tomatoes and taco seasoning in a bowl and whisk until combined. Spread into an even layer in a 7"x11" casserole dish.
In a separate bowl combine the avocado, lime juice, cilantro and garlic salt. Mash until desired consistency is reached and then spread into an even layer over the beans.
Stir the sour cream until nice and smooth, then spread into an even layer over the guacamole.
Sprinkle the shredded cheese over the top of the sour cream, then top with the diced tomatoes, black olives and green onions.
Cover with plastic wrap and keep chilled until ready to serve.
Notes
Dip can be made up to 2 days in advance, and stored for up to 5 days in the refrigerator. Just keep in mind that the guacamole can turn brown when exposed to oxygen.