1. Preheat your oven to 400°F (200°C).
2. Heat a skillet over medium heat and cook the ground beef until browned. Drain excess grease and add the taco seasoning according to packet instructions. Set aside.
3. Heat the refried beans in a microwave-safe bowl until warm.
4. In a separate skillet, heat vegetable oil over medium-high heat.
5. Fry each tortilla for about 1-2 minutes on each side until crispy. Drain on paper towels.
6. To assemble each Mexican pizza, spread a layer of refried beans on one tortilla, followed by a layer of seasoned ground beef.
7. Place another tortilla on top and spread a layer of diced tomatoes and sliced black olives (if using) over the beef.
8. Sprinkle shredded cheese on top.
9. Repeat to make another Mexican pizza.
10. Place assembled pizzas on a baking sheet and bake in the preheated oven for 5-7 minutes or until the cheese is melted and bubbly.
11. Serve hot with optional toppings like diced green onions, sour cream, and salsa.