Preheat your oven to 375°F (190°C). Lightly grease an 8x8 inch baking dish or a similar sized oven-safe pie plate.

In a large bowl, combine the softened cream cheese, sour cream, 3/4 cup of mozzarella cheese (reserving the final 1/4 cup for topping), ranch dressing mix, and Parmesan cheese. Mix thoroughly until completely smooth and well combined.

Spread the cream cheese mixture evenly into the bottom of the prepared baking dish. This forms the base layer.

Gently spoon the pizza sauce over the cream cheese layer, spreading it carefully with the back of a spoon, ensuring an even coating without disturbing the base too much.

Scatter the prepared toppings (black olives, green pepper, red onion, and mushrooms) evenly over the sauce layer.

Sprinkle the remaining 1/4 cup of mozzarella cheese over the top of all the vegetables.

Bake for 18-20 minutes, or until the dip is hot throughout and the cheese on top is melted and bubbly. For extra browning, broil for the last 1-2 minutes, watching closely.

Let the dip cool for about 5 minutes before serving warm with tortilla chips, pita bread triangles, or sturdy crackers.