Preheat the Oven
Preheat your oven to 350°F (175°C).
Cook the Ground Beef
In a skillet over medium heat, brown the ground beef until fully cooked. Drain any excess grease.
Add the oats and all the beef seasoning ingredients (except the cornstarch). Stir to combine.
Add ¼ cup of water and simmer until the liquid has reduced by half, about 5 minutes.
Mix in the cornstarch and cook for another 3–4 minutes until thickened. Remove from heat and set aside.
Assemble the Tortilla Layers
Spread a layer of refried beans evenly across four tortillas.
Add a layer of the cooked beef mixture on top of the beans.
Place another tortilla on top of each beef-and-bean layer to create a sandwich-style base.
Prepare the Enchilada Sauce
In a small bowl, combine the enchilada sauce, sugar, onion powder, and green chili juice. Mix well.
Top the Mexican Pizzas
Spread a thin layer of the enchilada sauce over the top of each tortilla stack.
Sprinkle the diced tomatoes evenly across the top, followed by the three-cheese blend (cheddar, mozzarella, and Monterey Jack).
Bake the Pizzas
Place the assembled pizzas on a baking sheet and bake for 10–15 minutes, or until the cheese is melted and bubbling.
Serve and Enjoy
Remove from the oven and let the pizzas cool slightly before slicing into quarters. Serve warm and enjoy!