Step 1: Preheat oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish.
Step 2: Heat olive oil in a large skillet over medium-high heat. Add ground beef and cook, breaking it apart with a spoon, until browned. Drain off any excess fat.
Step 3: Add chopped onion and minced garlic to the skillet with the beef. Cook for 5-7 minutes, or until the onion is softened.
Step 4: Stir in the taco seasoning and the can of undrained diced tomatoes with green chilies. Bring the mixture to a simmer and cook for 5 minutes, allowing the flavors to meld and the sauce to thicken slightly. Remove from heat.
Step 5: Spread about 1/2 cup of enchilada sauce evenly over the bottom of the prepared baking dish.
Step 6: Arrange a single layer of corn tortillas over the sauce, overlapping them slightly as needed to cover the bottom of the dish. You may need to cut some tortillas to fit the shape.
Step 7: Spread half of the refried beans evenly over the tortilla layer.
Step 8: Spoon half of the seasoned ground beef mixture over the refried beans.
Step 9: Sprinkle generously with 1/3 of the combined shredded Monterey Jack and Cheddar cheeses.
Step 10: Place another layer of tortillas over the cheese. Repeat with the remaining refried beans, the rest of the ground beef mixture, and another 1/3 of the cheese.
Step 11: Top with a final layer of tortillas. Pour the remaining enchilada sauce over the top, spreading to ensure all tortillas are covered.
Step 12: Sprinkle with the remaining cheese.
Step 13: Cover the baking dish loosely with aluminum foil and bake for 25 minutes.
Step 14: Remove the foil and continue baking for an additional 15-20 minutes, or until the cheese is bubbly and lightly golden brown.
Step 15: Let the Mexican Lasagna rest for 10-15 minutes before slicing and serving. Garnish with fresh cilantro, avocado slices, and a dollop of sour cream or Mexican crema.